The Knowledge of London

The World's Toughest Geography Test

Steve Scotland had better reason than most for thinking he knew London like the back of his hand. Not only was he a native Londoner, born and bred, but he’d spent years working as a chauffeur in the city, driving his passengers wherever they wanted to go, finding the shortcuts, negotiating the city’s traffic-clogged streets swiftly, accurately and with a minimum of fuss and bother.

And so he quietly fancied his chances of doing ‘The Knowledge’ – the demanding test of London’s backstreets and landmarks that has to be passed by anyone who wishes to join the elite and pleasantly well-paid ranks of London’s black cab drivers.

“It was something I always wanted to do,” he said.

And so in pursuit of this dream he took himself down to the Public Carriage Office, which regulates taxis in London, and signed on to do The Knowledge. After paying his fees and sitting a map test and some written exams, he got hold of a motor scooter and set off to familiarise himself with the myriad streets, roads, avenues, courts, lanes, crescents, places, mews, yards, hills and alleys that go to make up the map of London.

Nearly five years later, and with more than 10,000 miles clocked on his scooter, he is still at it, although now at least it’s with an end in sight. A good enough score on his next test, or ‘appearance’, in a fortnight’s time, and he’ll have done it – cracked The Knowledge and earned himself the coveted green-and-white badge of a London cabbie. “I had no idea how tough this would be,” he says. “I really thought I knew the city well, but what I knew, or thought I knew, was nothing compared with what it takes to do The Knowledge.”


For more than 150 years London cabbies have been required to be the consummate experts on their city. Hail a black cab from anywhere you please within the greater metropolitan area, tell the driver where you want to go – it doesn’t matter whether it’s The Tower of London or some obscure pub in an outer suburb – and by the time you’ve climbed in the back seat and closed the door they will have already calculated the swiftest, most direct route to get there – without ever looking at a map.

Even if you’re not quite sure where you want to go, say you’re a tourist and you’ve reserved tickets to see The 39 Stepsand you’re picking them up at the box office but you can’t recall the name of the theatre – just give the name of the play; your cabbie will take you, in this case, straight to the Criterium, on Piccadilly Circus. Not only do they know all the theatres, they keep abreast with what’s playing where.

They don’t just happen to know these things. Anyone holding a cabbie’s license in London has had to pass ‘The Knowledge of London’ – the toughest geography test in the world. It has been this way for over 150 years. The whip-cracking drivers of those Victorian hansom cabs that Sherlock Holmes was forever hailing, all had to have done The Knowledge just as the 25,000-odd drivers of London’s iconic black cabs have to do today.

Even in these days of GPS and Google Maps, a Sat Nav is no match for a cabbie with The Knowledge. Indeed, last May London’s Guardian newspaper pitted a London cabbie against a Sat-Nav equipped driver from Uber, the sleek new ‘taxi’ company that is taking the world’s cities by storm by allowing users to book hire cars via their smartphones. The Uber driver did the run from the newspapers office in King’s Cross to Big Ben, in Westminster in 22 minutes; the bemused cabbie did it in 18, by taking a  slightly longer route that he knew to be quicker.

It’s not simply a matter of speed. “I like to put it this way,” says 18 year veteran cabbie David Styles, who writes a blog on London and life behind the wheel. “When gentlemen have enjoyed supper at their club with their old regimental chums they need a taxi to take them to the station. As they can generally afford to live in East Sussex, their station, Victoria, is only six minutes from Pall Mall. Depending on which entrance they want they ask for ‘The Shakespeare’; ‘Old Gatwick’; or ‘Hole in the Wall’. Show me a Sat-Nav which not only has that database but can be programmed in seconds and I’ll buy shares in it myself.

“And actors don’t want to arrive at the front of the theatre. They want the stage door. And yes we have to learn those too.”



Forget Mensa and its armchair brain-teasers. ‘The Knowledge of London’ is one of the toughest mental challenges ever devised, a real-time street-level test of memorisation skills so intense that it literally, physically, alters the brains of those who can pass it. Most people can’t. And as a result they will never drive a black cab in London.

No other city in the world demands as much from its cabbies. To qualify for that elusive green badge, you need to learn by heart all 320 sample runs that are listed in the Blue Book, the would-be cabbie’s bible, plus commit to memory the 25,000 streets that lie within a six-mile radius of Charing Cross, plus the locations of another 20,000 landmarks and points of interest – pubs, clubs, museums, parks, monuments, railway stations, tube stations, hospitals, schools, police stations, government buildings, embassies, cemeteries, churches, guild halls, theatres, cinemas – anyplace a hypothetical fare-paying passenger might conceivably ask to be taken, or an examiner might challenge you to find.

You need to know your way around so well that when asked you can calculate the most direct legal route between any two addresses anywhere in the entire 113 square-mile metropolitan area within a matter of seconds, without looking at a map, and be able to rattle off the precise sequence of streets, junctions, roundabouts, and left- and right-hand turns that would be necessary to complete such a journey.

And you have to be able to do this consistently, not just once or twice, but in a potentially endless series of one-on-one oral exams, called ‘appearances’, taken at regular intervals until the examiners are satisfied that you do indeed possess The Knowledge.

Indeed, Scotland would have already had his badge a few weeks ago, at his last appearance, had he not miscued a turn and dropped his hypothetical passenger off on the wrong side of the street. “Just nerves,” he recalled. “All I had to do was pick up at the cab rank at Sainsbury’s (supermarket) on Liverpool Street and drop off at the emergency entrance at the Moorfield’s Eye Hospital. That’s a run I can do in my sleep.”

But he didn’t do it when it counted and as a result, instead of spending this Sunday afternoon sitting home watching the World Cup, as he’d been looking forward to, he is once more astride his scooter, still a ‘Knowledge Boy’, puttering along Great Swan Alley, just off Copthall Avenue, in London’s financial district, brushing up ahead of his next – and hopefully final – appearance. “A new restaurant has opened up around here and I want to get it fixed in my mind – just in case,” he says. “You just never know what the examiners are going to ask you.”



The nearly five years Scotland has spent thus far on the quest – enough time to do a university degree from scratch – is not unusual among Knowledge students. “It took me four years, eleven months and thirteen days,” recalled cabbie and blogger David Styles.

While a fortunate few, those who can afford to pursue it full time, can complete the training in as little as two years, most have to fit in The Knowledge around work and family commitments. “I’m guessing it’ll take me around five years,” says 53 year-old David Greenhalgh, an IT specialist turned Knowledge Boy who has spent the past two years juggling The Knowledge with his day-job and reckons he has another three before he can finish.

Like Scotland he is taking advantage of the weekend quiet in the city, in his case exploring the tangled backstreets in the neighbourhoods between Cannon Street Station, London Wall and St Paul’s Cathedral. He is on foot, with a rucksack slung over his shoulder and guide to the city’s 110 livery halls – just some of the thousands of ‘points of interest’ whose locations he will need to know by heart.

In the past couple of hours he has tracked down the Worshipful Company of Mercers, the oldest of London’s livery companies, founded in 1394, the grandiose building housing the Worshipful Company of Vintners (on Upper Thames Street), and the Worshipful Company of Stationers and Newspaper Makers, in a secluded square off Ave Maria Lane.

On such a fine warm summery Sunday afternoon as this, doing The Knowledge, in the form of a quixotic nosing about for London’s old livery halls seems like the pleasantest kind of tourism – sightseeing with a purpose. “It’s not always like this,” Greenhalgh laughs, as he pauses to photograph the ornate portal to the Worshipful Company of Apothecaries, whose 17thcentury headquarters is hidden away down a picturesque cobbled lane, not far from Blackfriar’s Station. “You have to get to know the dodgy neighbourhoods too.”

Only about one in five of those who attempt The Knowledge will ever make the grade. “You can never actually fail The Knowledge,” says Styles, “There’s only quitting. You’re allowed to keep trying as long as you like.” The overwhelming majority drop out in frustration after a year or so.

To put the success rate into perspective, the percentage of people who successfully complete The Knowledge is roughly the same as the percentage of candidates who make it through the training to become a U.S. Navy SEAL.

“There are no shortcuts,” says 79 year-old cabbie Alf Townsend, who did The Knowledge in 1962 and still drives his cab a few hours a day, to mingle with old friends and keep his hand in. “You can’t do it by sitting at home, memorising maps and street names and hope to pass that way. You have to get out on the streets, putting in the miles, seeing and experiencing everything first hand. There’s no other way.”



It was King Charles I, in 1636, who launched London’s taxi service – making it the oldest in the world – by granting royal permission for 50 hackney carriages to ‘ply their trade’ on the streets of the city, and Oliver Cromwell a few years later, in 1654 who set up the framework of regulations under which it operated, but it was a stern Victorian police commissioner, Sir Richard Mayne, who set up The Knowledge.

Dismayed by the number of complaints from visitors at the Great Exhibition of 1851 that London cabbies didn’t seem to know where they were going, he made it a requirement that anyone seeking a cabbies license be an expert on the city. And so The Knowledge was born.

Although the city has changed out of all recognition since then, the demands of The Knowledge have changed little. Then as now the idea is simple: that anyone hailing a London cab, from anywhere in that six-mile radius of Charing Cross, should be able to expect the driver to take them directly to their destination by the shortest legal route without once having to stop and consult a map.

To create a framework for studying and testing, a series of sample cab runs through the city were worked out by the Public Carriage Office. A candidate who mastered them all, knew them by heart, as well as the streets and landmarks in a quarter mile radius around each start and end point, could be considered to have The Knowledge. The precise number of runs has varied over the years, but today stands at 320, and are found in the Blue Book – which is actually pink.

“In some ways people doing The Knowledge today have it easier than we did 50 years ago,” says Townsend. “We had to figure out the shortest routes for ourselves, sticking pins in maps at the end points, tying threads between them then trying to work out the route that stayed closest to the thread – being ‘on the cotton’ it was called. Nowadays you can buy books and apps that have the correct routes already worked out for you.”

There are also Knowledge Schools, taught by veteran cabbies, to help candidates learn the runs and prepare for the exams. The examiners too are said to be more reasonable – still austere, but a bit less like Royal Marine drill sergeants and a bit more like Mr Chipps.

There’s better wet-weather gear now too, says Townsend; no small consideration to anyone who has to ride thousands of miles around the back streets of soggy old London town on a scooter.  “I nearly froze, “ he recalled. “All I had was a garbage bin-liner over me to keep out the rain, a waterproof fisherman’s hat and a couple of my wife’s scarves wrapped around my neck to try to keep me warm. Nowadays they have Gore-Tex and heated gloves.”



Some things never change.  Manor House Station to Gibson Square is still the very first of the 320 Blue Book runs that a would-be cabbie is expected to know.

“I started out very early one Sunday morning,” recalls Rob Lordan, a 33-year-old former school teacher who became a cabbie a little over four years ago. “I remember it was eerily quiet. I felt as though I had the entire city to myself. I was full of excitement, very much looking forward to exploring and learning London.”

This traditional first run, he discovered, was gratifyingly easy to learn – a reasonably straightforward journey, 2.9 miles long, between a nondescript tube station on the Piccadilly Line and a quiet square in fashionable Islington. “I’d prepared considerably beforehand, poring over the map and, being a beginner, I drove it several times to make sure I was familiar with every turn and junction.”

Then he moved onto the next run, and the next. “On average, I would spend 3 to 4 hours on each run,” he recalls. To master a route for testing purposes a student has to memorise not just the streets linking the two end points, but be intimately familiar with the backstreets and landmarks for a quarter-mile radius around both the beginning and the end. “An examiner quizzing you on a run is never going to ask you anything straightforward like ‘take me from Manor House Station to Gibson Square’,” Lordan says. “He’ll always pick some address that’s just around the corner or a couple streets away.”

Initial enthusiasm soon wanes in the face of the mind-boggling complexity of London’s labyrinthine streets and the sheer frustration in trying to learn them all. “There comes a time, about a year into it, when you really begin to doubt what you’re doing,” says Lordan. “For me it was the intricate one-way systems and myriad dead-ends in parts of north London, especially around Islington. They had me pulling my hair out. I didn’t think I was ever going to get those straight.”

Eventually though, he says, with persistence, there comes a tipping point, when it all starts to make sense. “It’s like putting together a jigsaw puzzle. Suddenly you see it. You spend so much time on the streets and studying the map at home that it etches itself on your brain. An analogy I like to use is that it reminded me of starting secondary school as a child. At first, the building seemed huge with its many rooms, wings and corridors. But after a while, you get to know the place and navigating it becomes second nature.”


It’s a good analogy. A study by neurologists at University College London found that the hippocampis – the segment of the brain responsible for spatial navigation – of London cabbies were significantly larger than in the rest of the human population as a result of the intense memorisation and route finding undertaken while doing The Knowledge.

The study involved taking regular brain scans of Knowledge students while they were undergoing their training and comparing them with scans taken of a control group who had no interest in becoming cab drivers. At the beginning of the study, the hippocampus in the brains of all the subjects were of similar size and all of the subjects performed similarly well on routine memory and route finding tests.

By the end of the study, the hippocampus of those who had succeeded in passing The Knowledge had grown significantly and what’s more continued to grow the longer they worked as cabbies.

“We don’t know what is changing in the hippocampi of taxi drivers,” says Professor Eleanor Maguire, who led the study. “Whether it’s new neurons that are being produced, new connections between neurons, proliferation of other cell types, or all three.”

“There has been a lot of research looking at trying to associate different brain areas with certain skills – musicians, or linguists for example. The key point about London taxi drivers is that they acquire their navigational expertise when they are adults unlike musicians who often start when children and so there is the added factor/complication of the interaction between brain development and skill acquisition.”


Certainly the hippocampis of would-be London cab drivers get a lot of intensive exercise.  Every day David Greenhalgh recites at least 30 of the 320 runs he has memorised – every turn, junction and roundabout. “I work my way up through the list and then start all over again.” Reciting these runs is known as ‘calling over’. Knowledge students often get together to recite them to each other. For example, the call over for Manor House Station to Gibson Square would be:

Leave on left – Green Lanes
Right on Brownswood Road
Left on Blackstock Road
Forward on Highbury Park
Forward on Highbury Grove
Right on St Pauls Road
Comply Highbury Corner
Leave Upper Street
Right on Barnsbury St
Left on Milner Sq
Forward on Milner Place
Forward to Gibson Square



After the 320 runs are memorised, the Knowledge student begins the long battery of oral tests that – hopefully, one day – will lead to their green badge. The first are called 56-day appearances, given every eight weeks. The examiner asks you to do four runs,” says Greenhalgh, who has done two 56-day appearances thus far. “Each run is worth ten points. If you get a perfect score of 40 – something that’s phenomenally rare – you get an A and advance straight up to the next level, your 28-day appearances.”

Lesser scores are awarded B or C or D grades, and the student returns in 56 days to try again. Grading is strict. Points are deducted for ‘hesitancy’, while making an illegal turn or going the wrong way up a one-way street earns you a big fat zero. To advance to the next level of testing a candidate needs the equivalent of two ‘B’ grades, or four ‘C’s.

A ‘D’ gets you nowhere.

If after seven attempts you’ve not scored well enough to pass onto your 28-day appearances, the slate is wiped clean and you start your 56-day tests all over again – something that happens to as many as 80 per cent of first time Knowledge students.

Otherwise you move up to your 28s – with the exams now coming every four weeks – and begin the process of testing and accruing points to move onto your 21-day appearances, the final tier, with the questions becoming more and more challenging each time.

Pass your 21s and you’re there. “It’s a very emotional moment when you realise you’ve done it and get that handshake from the examiner,” says Lordan, who passed just before Christmas four years ago. “I know I got quite teary. They tell me a lot of guys cry when they get their badge – you’ve invested so much of yourself, your time and your life, into doing this, to reach the end is just incredible.”



We are standing beside an old green Victorian cabman’s shelter on Russell Street – one of 13 still in existence around the city, where cabbies can get mugs of tea and bacon sandwiches and take a rest inside. With the ease and fluency of a man who has The Knowledge, and the passion of a true historian, Lordan tells me the history of the cabmen’s shelters in London, how they were founded by a Captain Armstrong in 1875 to give the taxi drivers somewhere to keep warm and dry. “He sent his manservant out to hail a cab in a blizzard.  He came back an hour later and said they were all in pubs, trying to keep warm, and none of them were in any fit state to drive. And so he established this of shelters.”

Lordan is one of a small percentage of cabbies who have gone on and obtained their green badge as a licensed tour guide as well. “Doing The Knowledge has made me somewhat obsessive,” he laughs. “I’m constantly striving to improve my grasp of the city, to learn as much as I can. I love this job. I am always learning something new. As Samuel Johnson said, a man who’s tired of London is tired of life.”