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The Knowledge, Londons Legendary Taxi-Driver Test, Puts Up a Fight in the Age of GPS - The New York Times

They call this area Fish Island, McCabe said. Im not much of a fisherman, but many of the roads here are named for fishes freshwater fishes, I believe. So just here youve got Bream Street. He gestured down a road where a lumberyard was set back behind a corrugated metal fence. Follow that to the end, youll come to Dace Road. Youve got Roach Road. All names of fishes.

McCabe had spent the last three years of his life thinking about Londons roads and landmarks, and how to navigate between them. In the process, he had logged more than 50,000 miles on motorbike and on foot, the equivalent of two circumnavigations of the Earth, nearly all within inner Londons dozen boroughs and the City of London financial district. He was studying to be a London taxi driver, devoting himself full-time to the challenge that would earn him a cabbies green badge and put him behind the wheel of one of the citys famous boxy black taxis.

Actually, challenge isnt quite the word for the trial a London cabbie endures to gain his qualification. It has been called the hardest test, of any kind, in the world. Its rigors have been likened to those required to earn a degree in law or medicine. It is without question a unique intellectual, psychological and physical ordeal, demanding unnumbered thousands of hours of immersive study, as would-be cabbies undertake the task of committing to memory the entirety of London, and demonstrating that mastery through a progressively more difficult sequence of oral examinations a process which, on average, takes four years to complete, and for some, much longer than that. The guidebook issued to prospective cabbies by London Taxi and Private Hire (LTPH), which oversees the test, summarizes the task like this:

To achieve the required standard to be licensed as an All London taxi driver you will need a thorough knowledge, primarily, of the area within a six-mile radius of Charing Cross. You will need to know: all the streets; housing estates; parks and open spaces; government offices and departments; financial and commercial centres; diplomatic premises; town halls; registry offices; hospitals; places of worship; sports stadiums and leisure centres; airline offices; stations; hotels; clubs; theatres; cinemas; museums; art galleries; schools; colleges and universities; police stations and headquarters buildings; civil, criminal and coroners courts; prisons; and places of interest to tourists. In fact, anywhere a taxi passenger might ask to be taken.

If anything, this description understates the case. The six-mile radius from Charing Cross, the putative center-point of London marked by an equestrian statue of King Charles I, takes in some 25,000 streets. London cabbies need to know all of those streets, and how to drive them the direction they run, which are one-way, which are dead ends, where to enter and exit traffic circles, and so on. But cabbies also need to know everything on the streets. Examiners may ask a would-be cabbie to identify the location of any restaurant in London. Any pub, any shop, any landmark, no matter how small or obscure all are fair game. Test-takers have been asked to name the whereabouts of flower stands, of laundromats, of commemorative plaques. One taxi driver told me that he was asked the location of a statue, just a foot tall, depicting two mice sharing a piece of cheese. Its on the facade of a building in Philpot Lane, on the corner of Eastcheap, not far from London Bridge.

If you go to LTPH headquarters, where the examinations are conducted, you will behold a grim bureaucratic scene, not much different than the one you might find in an office devoted to tax audits: nervous test-takers, dressed in suits, shuffling into one-on-one sessions with stone-faced examiners. But for more than a century, since the first green badge was issued to a hackney cabman piloting a horse-drawn carriage, the test has been known by a name that carries a whiff of the occult: the Knowledge of London.

Photo Some trace the origins of the Knowledge to the Great Exhibition of 1851, when visitors to London complained about inept hackney carriage drivers. Credit Popperfoto/Getty Images

The origins of the Knowledge are unclear lost in the murk of Victorian municipal history. Some trace the tests creation to the Great Exhibition of 1851, when Londons Crystal Palace played host to hundreds of thousands of visitors. These tourists, the story goes, inundated the city with complaints about the ineptitude of its cabmen, prompting authorities to institute a more demanding licensing process. The tale may be apocryphal, but it is certain that the Knowledge was in place by 1884: City records for that year contain a reference to 1,931 applicants for the examination as to the knowledge [of]principal streets and squares and public buildings.

In 2014, in any case, the Knowledge is steeped in regimens and rituals that have been around as long as anyone can remember. Taxi-driver candidates known as Knowledge boys and, increasingly today, Knowledge girls are issued a copy of the so-called Blue Book. This guidebook contains a list of 320 runs, trips from Point A to Point B: Manor House Station to Gibson Square, Jubilee Gardens to Royal London Hospital, Dryburgh Road to Vicarage Crescent, etc. The candidate embarks on the Knowledge by making these runs that is, by physically going to Manor House Station and finding the shortest route that can be legally driven to Gibson Square, and then doing the same thing 319 more times, for the other Blue Book runs.

But the Knowledge is not simply a matter of way-finding. The key is a process called pointing, studying the stuff on the streets: all those places a taxi passenger might ask to be taken. Knowledge boys have developed a system of pointing that some call satelliting, whereby the candidate travels in a quarter-mile radius around a runs starting and finishing points, poking around, identifying landmarks, making notes. By this method, the theory goes, a Knowledge student can commit to memory not just the streets but the streetscape the curve of the road, the pharmacy on the corner, the mice nibbling on cheese in the architrave.

Decades ago, most Knowledge boys did their runs on bicycles. Now, nearly all test-takers buy or lease motorbikes. In 2014, there are thousands of men and women plying the citys streets on two wheels, at all hours, in all weather, doing runs and gathering points. Its a ubiquitous London sight: a Knowledge boy on a bike, with a map or notepad strapped to his Plexiglas windscreen. When the candidate has completed his 320 Blue Book runs and his accompanying 640 quarter-mile radii point-gathering expeditions he will have covered the whole of central London. At which time he takes a brief written exam, proceeds to the first stage of the oral examination process, and the test begins in earnest.

Photo While studying for the Knowledge, aspiring taxi drivers practice runs by motorbike, with a map strapped to the windscreen. Credit Bloomberg

The testing takes place at the LTPH office in a series of appearances, face-to-face encounters between Knowledge candidate and examiner. The test-taker is asked to call a run: to identify the location of two points and to fluidly recite the shortest route between the points, naming all the streets along the way. A Knowledge boy is first given 56 days between appearances to study; then, as he progresses, 28 days, and 21. The questions, meanwhile, get harder, with candidates asked to locate more obscure points and to recite longer, more byzantine journeys across Londons byways. Each appearance consists of four runs, and each run is scored according to an elaborate numerical system. Your total score earns you a letter grade, from AA to D. (AAs are exceedingly rare; Ds arent.) Candidates who acquire too many bad grades are bumped backward red-lined from appearances every 28 days back to every 56 days, or from 21s to 28s. There is no such thing as failing the Knowledge. You can either quit, or persevere and pass: proceed all the way through to the end of your 21-day appearances, gaining sufficient points to earn your req to meet the required standard, and complete the test.

For Matt McCabe, that goal was within spitting distance. He was on 21s, on six points, making appearances just three weeks apart, with six points on his tally, and only six more needed just two solid appearances, perhaps, away from getting his req.

It was a pointing mission that brought McCabe to Fish Island that morning in January. Hed visited the neighborhood before, but had heard that a new point had come up in a candidates appearance a couple of days earlier. So hed returned to take another look at the area in particular, at H. Forman & Son, a wholesale fishmonger on Stour Road.

Photo McCabe on a "pointing" mission in Fish Island, an industrial district in East London. Credit Jody Rosen

Formans is quite famous, McCabe said. He was standing outside the H. Forman & Son warehouse, a shedlike structure the size of a small airplane hanger. They supply fish to the top restaurants in London. But now theyve opened their own restaurant. McCabe scrutinized the menu posted on a wall outside the building. He took a note on a small pad: Chef: Lloyd Hardwick. Hardwick, McCabe discovered by checking Google, had been the executive chef at the sleek restaurant on the top floor of the Tate Modern museum. You have to look into these things. You know, the examiner could turn around and say, Name me two Angela Hartnett restaurants, or Name me four Gordon Ramsay restaurants. McCabe showed me a sign indicating that the restaurant also housed an art gallery. Youve got to note that. Instead of Formans restaurant, the examiner might give you Formans Smokehouse Gallery. That could be enough to throw you off.

McCabe said: This is an up-and-coming area. It looks like nothing, you know but you put a bit of paint on the brickworks, smarten the place up, and all of a sudden it becomes a spot for little boutique stores or the up-and-coming D.J.s. Youve got warehouse conversions; youll see guys coming out of the buildings in the morning suit-and-tie, briefcase. If youre driving a cab, you could pick someone up in the City at the end of the day heading back this way.

McCabe had spent his entire professional life in the building trade. Hed worked alongside his father, an electrical engineer, and then as the owner of his own small firm specializing in roof maintenance, steel work and asbestos removal. He liked the work, but it was grueling 15-hour days, seven days a week and the 50,000 ($80,000) he took home wasnt enough, to his mind, to justify the sacrifices. A job as a taxi driver seemed an attractive alternative. London cabbies are self-employed businessmen who set their own schedules. The metered fares of taxis are high, and drivers keep what they earn. The overhead the cost of gas and of owning or leasing a taxi can be steep, but cabbies who put in the hours can make a good living. There are no official statistics, but drivers themselves will tell you that London cabbies can earn around 65,000 per year, about $100,000, while maintaining an enviably flexible schedule. As a cabbie, McCabe figured, he could work seven, 10, 15 days straight and then take four days off to spend time with his wife Katie, a hairdresser, and their children, Archie, 4, and Lulu, 3. He sold his engineering outfit and devoted himself full-time to the Knowledge, living off the savings hed gained from the sale of his business.

It was now 37 months since hed paid the 525 enrollment fee to sign on for the test and appearances. The closer you get, the wearier you are, and the worse you want it, McCabe said. Youre carrying all this baggage. Your stress. Worrying about your savings. McCabe said that hed spent in excess of 200,000 on the Knowledge, if you factored in his loss of earnings from not working. I want to be out working again before my kids are at the age where someone will ask: What does your daddy do? Right now, they know me as Daddy who drives a motorbike and is always looking at a map. They dont know me from my past, when I had a business and guys working for me. You want your life back.

The Knowledge is notorious for snatching away lives, and for putting minds in a vise grip. Everything becomes about the Knowledge, McCabe said. My wife will be talking to me about plans or the kids, and its not even registering what shes saying. Because all Im thinking is, I cant turn right into that road in Hammersmith, can I? If you read the paper, or watch the news or a film, youre looking at the background. Oh, I know that road there.

McCabe said that he dreamed about the Knowledge: sometimes exhilarating visions of zooming through London streets, more frequently nightmares about unfamiliar roads or disastrous LTPH appearances. Often, McCabe would wake in the middle of the night and hurry downstairs to study the map. In his dining room, there were three maps: two jumbo London street plans one laminated on the dinner table and one tacked to the wall and an enlarged view of the W1 postcode, the bustling zone which stretches south from Marylebone to Piccadilly and east to Soho. McCabe had ledgers hed filled with jottings on topics like Small and Awkward Squares. There were also flashcards that McCabe had made up, listing a point on one side (Tooting Mosque, SW17) with information about its location and navigation on the other (Gatton Road, one way, access via Fishponds Road). McCabe stacked the cards in piles of 300; he had 40,000 in all. His home, he said, had become a library of the Knowledge.

But book-learning gets you only so far. Youve got to get out on the bike, McCabe said. When he was doing Blue Book runs, McCabe would ride the streets all night, leaving when his wife got home from work at 9 p.m. and returning at 4 in the morning. Pointing, McCabe told me, can be very cold, very lonely, very dangerous. One night, McCabe was out pointing on his motorbike when a driver slammed into him from behind. McCabe went over the roof of the car, but suffered just a few scrapes and bruises. The bike was totaled. Im stationary in the filter lane, and the car just came around the bend and hit me, McCabe said. This was on a road called Pound Lane. Right across from the fire station at the corner of Harlesden Road.

As McCabe progressed through the Knowledge, his pointing technique had become more refined. At the beginning you might go to the Savoy Hotel on the Strand, he said. Thats a famous point; everyone knows it. But you start to think: Whats a more obscure point on the Strand? So youll pick up the Coal Hole Public House a few doors along. You start looking at George Court and find a little bar called Retro, a gay bar that plays 80s music. You start thinking about the bits and pieces. Im at the stage now where Im looking at a new bar that just opened inside a cinema. Im picking up handbag shops, bowling alleys. You learn to kind of savor them little gems.

Photo Taxis from the ’30s, ’60s and the present day. Credit Clockwise from top left: E.F. Corcoran/Topical Press Agency, via Getty Images; Malcolm/Getty Images; Ben Stansall/Agence France-Presse Getty Images

It is tempting to interpret the Knowledge as a uniquely British institution: an expression of the national passion for order and competence, and a democratization of what P. G. Wodehouse winkingly called the feudal spirit, putting an army of hyperefficient Jeeveses on the road, ready to be flagged down by any passing Bertie Wooster. But the Knowledge is less a product of the English character than of the torturous London landscape. To be in London is, at least half the time, to have no idea where the hell you are. Every London journey, even the most banal, holds the threat of taking an epic turn: The guy headed to the corner newsagent makes a left where he should have gone right, blunders into an unfamiliar road, and suddenly he is Odysseus adrift on the Acheron. The problem is one of both enormity and density. From the time that London first began to spread beyond the walls surrounding the Roman city, it kept sprawling outward, absorbing villages, enlarging the spider-web snarl of little roads, multiplying the maze. Take a look sometime at a London street map. What a mess: It is a preposterously complex tangle of veins and capillaries, the cardiovascular system of a monster.

All metropolises are quirky, but in most of them efforts have been made to mitigate the idiosyncrasies, to make the cities legible, navigable, beautiful. In Manhattan and Chicago, planners tamed chaos with gridded street schemes; Baron Haussmann obliterated twisty medieval Paris with his sweeping grands boulevards, transforming the city into a linked chain of vistas, plazas and parks. London, though, makes no sense. It was the capital city of the greatest empire in history, yet it doesnt look or feel imperial. There are miles of monotonous ugliness, disrupted not by splendor, but by gentility the pretty whitewashed homes and stately squares in the well-heeled districts of West and North London. St. Pauls Cathedral sits at the back of a small semicircular plaza that is pinned-in by the office towers and bendy streets of the financial district. It is difficult to get a decent view of the most beautiful building in town.

The genius behind St. Pauls, the architect Christopher Wren, nearly became Londons Haussmann. Just days after the catastrophic Great Fire of 1666, Wren produced a plan to rebuild London as an Italian-style city, with wide boulevards that terminated in piazzas and raised stone quays. But the plan never gained traction. The explanation usually given is economic: If Chicago is an expression of American pragmatism, and Paris an ode to symmetry, then London is a monument to English mercantilism and love of private property, to the power of the bourgeois freeholders and shopkeepers, who clung too tightly to their little patches of land to permit the clearing of space for Wrens plan. In London, lucre trumps grandeur.

The result is a town that bewilders even its lifelong residents. Londoners, writes Peter Ackroyd, are a population lost in [their] own city. Londons labyrinthine roadways are a symbol and, perhaps, a cause of the fatalism that hangs like a pea-soup fog over the Londoners consciousness. Facing the dizzying infinitude of streets, your mind turns darkly to thoughts of finitude: to the time that is flying, the minutes you are running late for your doctors appointment, the hours ticking by, never to be retrieved, on the proverbial Big Clock, the one even bigger than Big Ben. You can see it every day in Primrose Hill and Clapham, in Golders Green and Kentish Town, in Deptford and Dalston. A nervous man, an anxious woman, scanning the horizon for a recognizable landmark, searching for a street sign, silently wondering Where am I? a geographical question that grades gloomily into an existential one.

Which is where the Knowledge comes in. It is a weird citys weird solution to the riddle of itself, a municipal training program whose graduates are both transit workers and Gnostics: chauffeurs taught by the government to know the unknowable.

If you follow your London A-Z Street Atlas halfway up Caledonian Road, in Islington, youll find Knowledge Point, the largest of Londons 10 schools dedicated to the test. The school occupies a nondescript two-story building, but you cant miss it: At all hours of the day, Knowledge boys motorbikes line the sidewalk out front. For several years in the 1990s, there was something else parked alongside the bikes: the steed of a mounted Metropolitan Police officer, who did the Knowledge on horseback, after, and during, his working hours.

The school offers specialized lectures on dozens of topics: Hotels Outside Central London, South West London Turnarounds, Barracks & Military Establishments, Lambeth & Waterloo. Pupils pick up trade secrets, the aides-mmoires and acronyms that have been passed between generations of Knowledge boys. Theres Cat Eats Well Then Shares Her Beef Gravy, a mnemonic denoting a path north from the Aldwych the crescent-shaped road that loops above the Strand along a sequence of one-way streets: Catherine, Exeter, Wellington, Tavistock, Southampton, Henrietta, Bedford, Garrick. To access C.A.B. the Chelsea, Albert, and Battersea bridges you take C.O.B.: respectively, Chelsea Bridge Road, Oakley Street and Beaufort Street. A series of streets running north to south through Soho Greek, Frith, Dean, Wardour are Good For Dirty Women.

But the majority of a students time at Knowledge Point is spent in two cramped rooms on the schools ground floor, where maps are arranged on flat tables and angled easels. These rooms are devoted to calling-over: sitting with a partner, taking turns reciting runs, in an effort to replicate the conditions of oral examinations at the LTPH office. Anytime you step into Knowledge Point you will find students, faces pinched in concentration, calling-over runs in the specialized jargon mandated by Knowledge examiners. A skilled caller a woosher, in Knowledge slang can sound like a slam poet or a rapper, whipping off street names and turnings in a pleasing syncopated rhythm as he races through London streets in his minds eye: Leave on the right Lillie Road, left Eardley Crescent, left Warwick Road, forward Holland Road, comply Holland Circus, leave by Uxbridge Road, forward and right Shepherds Bush Green. More often, what you will hear at Knowledge Point is the sound of strain: groans, hems and haws, cursing.

Photo At Knowledge Point School in Islington, candidates prepare for their oral exams by taking classes on topics like ‘‘South West London turnarounds,’’ reciting runs of streets with partners and learning aides-mémoires for London’s bridges. Credit Rory Van Millingen

Matt McCabe had been coming to Knowledge Point since he started on the test. A stickler for routine, he arrived each morning at 8:45. When the doors opened at 9, he would sit down across a table from his call-over partner, Steven Vine. I met McCabe and Vine at Knowledge Point one morning and watched them call-over. They spent hours switching off, settling into a patter of run-calling punctuated by mumbled expletives and other exclamations: good pull (when you correctly identify a tricky point), bad drop (when you forget a point or road that you should know), nice line (when your call sketches a nice straight path across the map).

Video

Applying the Knowledge

Matt McCabe calls-over a route to demonstrate just how many turns a London cabbie must take to get from Point A to Point B.

By London Sessions Productions on Publish Date November 10, 2014. . Watch in Times Video »

To call-over effectively is to find a golden mean between geography and geometry. The aim is not just to navigate cleanly, naming the right roads, but to make the shortest and most elegant line between points. While McCabe called-over a run, Vine followed along, tracing his partners route with a marker on the laminated map. When McCabe finished, he and Vine stretched a ball-bearing chain over the map to assess the straightness of his call. This practice is known as cottoning the run, a phrase that dates to the days when Knowledge boys would use lengths of cotton twine to measure their runs. They have a saying, Dont let the cotton strangle you, McCabe said. Its a reminder: Dont get too tied up in having the perfect line. Youre always trying to calculate: Which one would look the prettiest on the map? But sometimes you just gotta let it flow.

The London landscape throws up constant impediments to the ideal of traveling in a straight line: parks, railway yards, one-way streets. The Thames presents another challenge. Because the area below the river is referred to as South London, most people assume that the dozen central London bridges spanning the water stretch north-to-south. In fact, the Thamess flow is meandering; in places, the river crossings run along the opposite axis. (A Knowledge boy mnemonic instructs: East to West, Lambeth or Westminster Bridge is best.) At Knowledge Point, McCabe leaned over the map and pointed to the Kings Road in Chelsea. If you were going from here, say, all the way out to Canary Wharf, you might cross the river twice to make it the shortest line. So you might run it across Westminster Bridge and bring yourself back across Tower Bridge. That will be a straight line, because youre understanding the bends in the river.

At his late stage of the test process, McCabe found himself facing a novel problem: too much Knowledge. London now feels very small. At the beginning, you would be standing in Piccadilly and someone says to you, Take me to Kilburn, and you would say: Oh my God, that feels miles away. Now, I can take you endless amounts of ways. And thats the dilemma youve got now: you see too many options.

Seeing, for a Knowledge candidate, is everything at its heart, the Knowledge is an elaborate exercise in visualization. When McCabe called-over, he closed his eyes and toggled between views: picturing the city at street level, the roads rolling out in front of him as if in a movie, then pulling the camera back to take in the birds eye perspective, scanning the London map. Knowledge boys speak of a Eureka moment when, after months or years of doggedly assembling the London puzzle, the fuzziness recedes and the city snaps into focus, the great morass of streets suddenly appearing as an intelligible whole. McCabe was startled not just by that macroview, but by the minute details he was able to retain. I can pull a tiny little art studio just from the color of the door, and where its got a lamppost outside. Your brain just remembers silly things, you know?

The brains of London taxi drivers have attracted scholarly attention. Eleanor Maguire, a neuroscientist at University College London, has spent 15 years studying cabbies and Knowledge boys. She has discovered that the posterior hippocampus, the area of the brain known to be important for memory, is bigger in London taxi drivers than in most people, and that a successful Knowledge candidates posterior hippocampus enlarges as he progresses through the test. Maguires work demonstrates that the brain is capable of structural change even in adulthood. The studies also provide a scientific explanation for the experiences of Knowledge students, the majority of whom have never pursued higher education and profess shock at the amount of information they are able to assimilate and retain.

Video

Taking the Knowledge Test: An Animation

As Knowledge candidates progress through the test, the posterior hippocampus, the area of the brain known to be important for memory, grows and grows.

By Anthony Cotsifas on Publish Date November 10, 2014. . Watch in Times Video »

Historically, taxi driving has been a white working-class industry, dominated by East Londoners: first, the Irish, and later, cockneys and Jews. For a century at least, the London black taxi has been a vehicle of upward mobility, steering a path into the middle class. Todays Knowledge candidates include a new generation of London strivers. At Knowledge Point, there are nearly as many black and brown faces bent over maps as white ones, and in the clamor of voices calling runs you hear a variety of accents South Asian, West African, Caribbean mingling with the broad vowels and glottal stops of Estuary English.

The students are united by shared suffering, and by a common adversary. For a Knowledge boy, the LTPH examiners have a kind of mythic status, inspiring a mixture of fear, resentment and awe. Appearances are highly ritualized. Candidates heed longstanding Knowledge traditions, wearing suits and ties to appearances and addressing the examiners formally. McCabe said: Its: Yes, sir, three bags full, sir. You can sit in there and before youve even done anything, youve said sir 15 times.

Examiners insist that the formality is important, designed to inculcate a professional code and to prepare future cabbies for the ornery London public. But there is also humor, of a sort, in the testing room. For generations, Knowledge examiners have seized on the poetry of London nomenclature to craft cheeky runs: Snowman House to the ICE Train, Hamlet Gardens to the Globe Theatre, the Eye (the giant Ferris wheel on the South Bank of the Thames) to the Nose (a tiny sculpture, reputedly modeled on Lord Nelsons nose, embedded in Admiralty Arch). One examiner, Tony Swire, likes to quiz candidates about their lives and use that information to concoct runs, off the top of his head, that flaunt his own vast London Knowledge. When Swire learned that Matt McCabes wife was a hairdresser and that his children were named Archie and Lulu, he gave McCabe a run from the Mayfair salon of celebrity hairstylist John Frieda, the ex-husband of Scottish pop singer Lulu, to Archie Street, a tiny dead-end road in Bermondsey.

Photo Examiners are known for their various quirks — such as requesting routes without traffic lights or, in the case of the ‘‘Smiling Assassin’’ David Hall (above), favoring difficult South London runs. Credit Rory Van Millingen

At Knowledge Point, McCabe explained the quirks of various examiners. There was Mr. Gunning, who favors runs with difficult strictures: He likes to impose road closures, or to ask candidates to do runs while steering clear of streets with traffic lights. Ms. Gerald, one of two women examiners, specializes in runs with lots of novel points. Theres another examiner, Mr. Hall, McCabe said. Hes a tricky one. They have a nickname for him. Everyone calls him the Smiling Assassin.

David Hall is, in fact, quick with a smile. Hes 53 years old and bald-headed. He wears rimless glasses and dark suits and ties. I met him one afternoon at the LTPH office. He was sitting at the desk where he conducts examinations, with a large London map and various notes spread out in front of him. It isnt so bad in here, is it? he said. He nodded slightly towards the area down the hall where Knowledge candidates wait to be called in for appearances. You cant believe everything you hear.

Hall knows what its like to sit on the other side of the examiners desk. Like all examiners, he is a cabbie, a Knowledge graduate with many years of taxi-driving on his CV. He left school at age 16, and got a job in the confectionery department at Harrods before becoming an electronics engineer. At age 27, he decided to try for a career as a cabbie. Hall had a keen sense of direction and had always loved maps. He passed the Knowledge in less than two years.

Hall became an examiner in 2008, and soon developed the reputation that earned him the Smiling Assassin moniker: He was a kind man, with a warm, welcoming manner, who asked very difficult runs. It is common knowledge among test-takers that Hall supports Crystal Palace, the football team based in South East London, and that he lives somewhere nearby. He is known, and feared, for giving vexing South London runs. Matt McCabe had Hall in two appearances, when he was on his 28s. McCabe said: Hes fair, but very hard. Hell take you from Kensington or Chelsea and hell get you to run it down to Peckham or to Dulwich. Hell put you in the dilemma: Do I take Vauxhall Bridge or Battersea Bridge? Hes very technical. And hes very into South London.

Hall is also known for doing his homework. Examiners have to burnish their own Knowledge to keep a step ahead of examinees, reviewing road closures and traffic patterns, and, in their spare time, hitting the streets to pick up new points. Hall is a dedicated pointer. When I told a Knowledge boy that I was planning to interview Mr. Hall, he said: I heard he went out pointing on Christmas Day.

One afternoon, I met Hall outside Palestra House, the office tower in Southwark that houses LTPH. He was carrying a digital voice recorder and a clipboard with notes and maps, which hed drawn himself. We walked north, crossing the Millennium Bridge, which links the South Bank of the Thames with the City of London, and then turned east, following the thrumming traffic along Queen Victoria Street. At a corner, Hall started scribbling notes. You have to work out: How do the roads go? Is Queen Victoria Street curving there? Is Friday Street going north? At the end of Friday Street yep, youve got a forced left with a blue arrow. A Knowledge candidate needs to take a mental picture of the road or the arrow there. Hall drew an arrow on his map, indicating the forced left.

Just west of the intersection, on the north side of Queen Victoria Street, stood an elegant old church, with a spire that jutted above the surrounding buildings. Hall said: Thats St. Nicholas Cole Abbey. Its a Wren church. In fact, the church predated Wren by several centuries, but it was destroyed in the Great Fire, and Wren rebuilt it. Thats a point Ill ask occasionally I have done before. Im very fond of City of London churches.

Photo Knowledge candidates encounter London's architectural oddities while studying roads and landmarks. One curio is the clock above the entrance to Bracken House, a City of London office building, which displays the signs of the zodiac and features a likeness of Winston Churchill. Credit Keith Edkins

It is said that the Knowledge is as much about learning history as learning your way around. After completing the Knowledge, Hall undertook a years-long course of study to earn the blue badge of an official London tour guide. While Hall strolled around the City pointing logging road works and making notes about new restaurants and bars he led me on an impromptu walking tour: more Wren churches, medieval livery companies and guild halls marked with elaborate coats of arms, the Worshipful Company of Tallow Chandlers, the Innholders Hall, a carved likeness of Winston Churchills face in the center of a clock above the doorway of an office building. Toward evening, we made our way back along Queen Victoria Street, passing a massive three-acre building site, the future home of Bloomberg L.P.s European headquarters. The construction project had revealed further remains of the Temple of Mithras, a Roman ruin first discovered in 1954. The temple once stood on the banks of the Walbrook, a now-buried river that brought fresh water to Roman Londinium. Hall said: In the religion practiced here, they used to have seven ordeals. If you were a Roman soldier, one of the ordeals was to put you over a fire pit. If you could withstand that particular ordeal, you went to the next stage in that religion.

Hall said: The thing about London is, its forever changing. The old city is preserved, of course, but theres always a new city coming forth. There really is no end to the Knowledge. Its infinite.

The test-takers of a century ago who tottered their way to the Knowledge on bicycles earned a heady reward: not just a green badge, but something close to a guaranteed living. Todays Knowledge candidates are banking on that pattern holding, but history seems to be veering in a different direction. These days, a person can walk into the LTPH office and, with relatively minimal effort, acquire a license to drive one of Londons nearly 60,000 minicabs, a fleet that vastly outnumbers the approximately 25,000 black taxis. Minicab drivers do not have to demonstrate familiarity with London; an applicant is merely required to pass a background check and take a topographical test. Minicabs can also offer cheaper fares than taxis, whose metered pricing schemes are strictly regulated.

For years, the black taxi industry has decried minicabs as an inferior service that poaches business rightfully belonging to Knowledge graduates. But many consumer advocates regard minicabs as a welcome corrective a reasonably priced alternative to black taxis, whose hefty fares are beyond the reach of most Londoners. (A 2013 survey by the travel website TripAdvisor deemed Londons taxis the worlds most expensive, with an average cost per trip of 27, about $43.)

Photo In June, thousands of taxi drivers gridlocked London streets to protest against Uber, the smartphone app-based ride-sharing company. Credit Clockwise from top right: Carl Court/Agence France-Presse Getty Images; Andrew Testa for The New York Times (2)

In theory, there are rules in place that offer advantages to traditional London cabbies: Theirs are the only rides that can legally be hailed on the street. But times are changing, and curbside hailing may soon be as quaint a relic of old London as the clubman striding through Mayfair in his bowler hat and boutonniere. Recently, the London taxi trade has been roiled by the rise of Uber, the smartphone app-based ride-sharing company. On June 11, thousands of drivers staged a one-hour-long strike, gridlocking streets to protest what they view as Ubers illegal evasion of Londons metering laws. The Licensed Taxi Drivers Association, a black-cab advocacy group, has brought a series of lawsuits against Uber drivers. But at the demonstration, the cabbies anger was directed less at Uber, per se, than at Transport for London and Boris Johnson, Londons mayor, whom taxi drivers regard as a zealous deregulator, friendly to big business at their expense. (At the rally, cabbies held placards that read: Uber: Under Boris Exempt from Regulation.)

In his public statements on the matter, the mayor has walked a fine line. Londons black-cab trade is crucial to the fabric of the city, Johnson said. There must, however, be a place for new technology to work in harmony with the black cab, and we shouldnt unnecessarily restrict new ideas that are of genuine benefit to Londoners. Others are less hedging. In July, Forbes ran an editorial by staff writer John Tamny, extolling Uber as a disrupter of the taxi business and casting Londons cabbies as pass: Just as automation, free trade and general economic progress have allowed us to shed previously important skills such as sewing, farming, and yes, addition/subtraction, so does it allow us indeed, it requires us to shed once-relevant knowledge. . . . As for London, the GPS has, much to the chagrin of some cabdrivers with telegraphic memory, rendered their knowledge of one of the worlds great cities largely irrelevant.

Taxi drivers counter such claims by pointing out that black cabs have triumphed in staged races against cars using GPS, or as the British call it, Sat-Nav. Cabbies contend that in dense and dynamic urban terrain like Londons, the brain of a cabbie is a superior navigation tool that Sat-Nav doesnt know about the construction that has sprung up on Regent Street, and that a driver who is hailed in heavily-trafficked Piccadilly Circus doesnt have time to enter an address and wait for his dashboard-mounted robot to tell him where to steer his car.

Such arguments may hold for a while. But given the pace of technological refinement, how long will it be before the development of a Sat-Nav algorithm that works better than the most ingenious cabbie, before a voice-activated GPS, or a driverless car, can zip a passenger from Piccadilly to Putney more efficiently than any Knowledge graduate? Ultimately, the case to make for the Knowledge may not be practical-economic (the Knowledge works better than Sat-Nav), or moral-political (the little man must be protected against rapacious global capitalism), but philosophical, spiritual, sentimental: The Knowledge should be maintained because it is good for Londons soul, and for the souls of Londoners. The Knowledge stands for, well, knowledge for the Enlightenment ideal of encyclopedic learning, for the humanist notion that diligent intellectual endeavor is ennobling, an end in itself. To support the Knowledge is to make the unfashionable argument that expertise cannot be reduced to data, that theres something dystopian, or at least depressing, about the outsourcing of humanitys hard-won erudition to gizmos, even to portable handheld gizmos that themselves are miracles of human imagination and ingenuity. Londons taxi driver test enshrines knowledge as to use the au courant term an artisanal commodity, a thing thats local and homespun, thriving ideally in the individual hippocampus, not the digital hivemind.

You could also call the Knowledge the greatest tribute a city has ever paid to itself, a love letter more ardent than I N.Y. or anything else a Chamber of Commerce might cook up. The Knowledge says that London is Holy Writ, a great mystery to be pored over, and that a corps of municipal Talmudists must be delegated to that task. To the extent that the mystifying clichs hold that taxi drivers are Londons singers of songlines and fonts of folk wisdom, carrying not just the secrets of London navigation but the deep history of the city and its streets the disappearance of the Knowledge would be an assault on civic memory, a blow, if you will, to historic preservation. Smartphone apps and Google Maps may ensure that Londoners will never again be lost in their own city, but if the Knowledge disappears, will something of London itself be lost will some essence of the place vanish along with all those guys on mopeds, learning the towns roads and plumbing its depths?

Like most cabbies and Knowledge boys, Matt McCabe worries about the future of the taxi business. But in January 2013, he had more pressing concerns. A few days after his visit to Fish Island, McCabe went on an appearance and scored a B, leaving him with 10 points, just two shy of his goal. Barring a calamity, a brain-freeze, it seemed a foregone conclusion that his next appearance would be his last.

Three weeks later, on a Friday, McCabe rose, as usual, early, with his children, and went through a routine hed established over many months. He made sure he was cleanly shaven, that his shoes were polished, his suit pristine. He took the train into London, disembarked at London Bridge station, and walked to the LTPH office at a measured pace, trying to keep his heart-rate steady. He arrived with time to spare and took his seat in the waiting area with a dozen or so other Knowledge candidates.

At around 2 p.m., McCabes name was called, and he was ushered into the office of a man hed never met before. David OConnor is a veteran examiner with a reputation as a hard marker. McCabe knew that OConnor liked to test whether candidates had been getting around on the bike, and liked to give runs that worked the center of the map.

Photo McCabe Credit Rory Van Millingen

McCabe sat down and breezed through his first three runs. He was nervous, but his calls, he thought, were solid. Surely it was a done deed now? For the sessions final run, OConnor asked McCabe to take him from the Sun and Doves to Emirates Stadium. McCabe closed his eyes. He could see the Sun and Doves: It was a pub on the corner of Coldharbour Lane and Caldecot Road, down in Camberwell. Of course he knew Emirates Stadium, the home of Arsenal, the Premier League football team. McCabe said: Sun and Doves, Coldharbour Lane. Emirates Stadium, its Drayton Park. Thats the North Bank entrance. OConnor nodded: the Knowledge boy had identified the points correctly. McCabe closed his eyes again, to make sure he saw the line clearly. Then he called the run:

Leave on the right, Coldharbour LaneLeft into Denmark HillForward Camberwell RoadForward Walworth RoadComply Elephant and CastleLeave by Newington CausewayForward Borough High StreetForward over London BridgeForward into King William StreetForward Lombard StreetForward Bank JunctionForward Princes StreetForward MoorgateForward Finsbury PavementForward Finsbury SquareForward City RoadComply Old Street roundaboutLeave by City Road continuedRight Provost StreetRight Vestry StreetLeft into East RoadForward New North RoadForward Canonbury RoadComply Highbury CornerLeave by Holloway RoadRight Drayton ParkSet down on the left

It was a nearly seven-mile-long journey, due north, from Camberwell to Holloway, in Islington, north-central London. When McCabe finished the call, he and OConnor sat in silence for what seemed to McCabe an eternity. Finally, OConnor stood up and extended his hand. He said: Well done, Matt. Welcome to the club. Im pleased to say that youre now one of Londons finest. It was the first time in the more than three years McCabe had been coming to LTPH that an examiner had called him by his first name.

It was an emotional moment, McCabe said. It was hard to hold back the tears. Three years of complete financial stress, family stress studying for 13 hours a day, seven days a week. Suddenly, the whole thing was very casual. It was quite, you know, Sit back, relax, loosen your tie. And then Mr. OConnor was telling me what to expect doing the job. He was giving me his inside knowledge after being a London cabbie for, like, 20-odd years. McCabe went home to his family. He and his wife, Katie, ordered take-out from a Thai restaurant, put on loud music, and danced around the house with their children. When the kids went to bed, the McCabes drank a few beers and dismantled the Knowledge library: stored the flashcards and pages of notes, took the maps off the wall. Katie, McCabe said, cried for about two days solid.

McCabe has been driving a taxi for just over a year and a half. He is still new at the job, relatively speaking; in London cabbie lingo, hes a Butter Boy but a boy, a recent Knowledge graduate. He has the leanings of a traditionalist, though. Many cabbies today are opting for new minivan-style Mercedes taxis, or cabs decorated with full wrap-liveries, advertisements in eye-popping hues. McCabe owns a TX4 Elegance, a car with the classic London black cab look. I like the iconic shape, he said. To me, if youre gonna be a London cabbie, thats what you should be driving.

In June, McCabe took part in the demonstration against Uber. He said, Were trying to be the best in the world, and trying to stay competitive as well. And, you know, the way Uber seems to operate in London when its quiet, they do the work for next to nothing, when its busy, the rates are three times dearer than a London cab. For now, McCabe is making a good living. The rewards are there. You have to do the hours. I mean, a normal day for me is a 12-hour day.

He said: What Ive done is a trade. A minicab driver, an Uber driver they wont do the undertaking I done. They wont put in the three years.

I had a gentleman in the cab recently, McCabe said. He told me that a couple of nights earlier hed been eating in a restaurant in Chelsea, and the Uber car turned up. He said, We want to go to Wapping. And the driver said, Wheres Wapping? Is it in London? And its, like, a massive borough. Hes never heard of it! So, I picked this guy up. He said, Wapping. I went, Yes, sir. And he said, Kennet Street. I went, Yes, sir. He got in the back, and we were off. And he told me, Thats why Im reverting back to London cabs.

McCabe said, The moment a person tells me at the window where they want to go, were going. Theres no mucking about. I want to get you from A to B as quickly as possible. Because as nice as the person may be, I want to get them in and out. So I can get the next person in the back of the cab, and Im earning more money.

McCabe is still doing the Knowledge, after a fashion. Hes embarked on the three-year course to become a licensed London historian an official tour guide, like David Hall. Im fascinated with the quirky little bits of London history, McCabe said. The famous lamps at the Savoy. The secret tunnels that link up to St. Jamess Palace.

When hes in his cab, McCabe keeps his eyes peeled for another London curiosity: the Knowledge examiners, his erstwhile tormentors, now colleagues, who may be out driving their own taxis, or gathering new points. Each workday, McCabe makes his way into the citys center via South London, guiding his taxi through the streets that have flummoxed many a Knowledge boy attempting to call one of Mr. Halls runs. McCabe hasnt spotted Hall yet, but he hopes he will sometime. It would be nice, he says, to have a beer with the Smiling Assassin.

Back in the winter of 2013, shortly before McCabes final appearance, I asked him how he was handling the pressure. He said: If you overcome the nerves, your training will take over. When I get into that room, I try to think: This guy is an examiner, but when hes not sitting here, hes behind the wheel, driving a cab. He could pick me up tomorrow, you know, or pick my wife up. That calms me down. I think to myself, This guy is just a cab driver, same as what I want to be. Hes just a London cab driver. He doesnt know everything.

A version of this article appears in print on December 7, 2014, on Page M2170 of T Magazine with the headline: Lost Knowledge. Today's Paper|Subscribe

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