London taxi drivers are legendary for their encyclopedic grasp of the country's capital city and ‘the Knowledge’ - the assessment all wannabe London cabbies have to pass with flying colours - is notorious for being a mind-bendingly difficult slog. It can take around three to four years of hard training to pass, and according to Malcolm Linskey, manager of London taxi school Knowledge Point, three-quarters of those who embark on the course drop out.

Introduced by Sir Richard Mayne in 1851, ‘the Knowledge’ came about after customers complained that drivers didn’t know where they were going.

In addition to having quick-fire knowledge of some 25,000 streets within six miles of Charing Cross Station, London cabbies also have to know the capital’s notable landmarks and places of interest, as well as the location of London’s hospitals, police stations, courts, government buildings, train and underground stations and main parks.

In order to qualify for ‘the Knowledge’, applicants must have a clean driving licence, be over 21 years of age, and have no criminal record. The next step is to pass a written test; which qualifies them to make an 'appearance'.
As part of their training, hopeful cabbies follow need-to-know routes around London on a moped, identifying them as they go using the map holder fixed to the front of the bike, this then earns them the name knowledge boys (or girls). 

At appearances, knowledge boys (or girls) must, without looking at the map, identify the quickest and most sensible route between any two points in metropolitan London that their examiner chooses.

For each route the applicants must recite the names of the roads used and when they cross junctions, use roundabouts, make turns, and what is 'alongside' them at each point. How many of the routes (runs) and places of interest you need to know will depend on whether you want to be an All London or a Suburban driver.

Once prospective cabbies make it though all the hard-core training and pass the final exam, they receive the coveted green and gold medallion, which grants them with a licence to work - to pick up hailing punters in the street.

A cabbie navigation trick: “Little apples grow quickly” gives you the order of the theatres on the north side of Shaftesbury Avenue: Lyric, Apollo, Gielgud, Queen's.

Although ‘the Knowledge’ is probably one the most testing and brain-straining times a potential cabbie will ever go through, the rewards to be reaped are not to be sniffed at. Black cabbies are self-employed and can earn significantly more than minicab drivers. A black cab fare from Shepherd's Bush to Heathrow for example, might cost £50, compared with £28 for a minicab.

Furthermore, wannabe cabbies' brains will grow. Yes indeed, by learning (and then regularly using) ‘the Knowledge’, the part of the brain associated with navigation (which is associated with navigation in birds and animals) will grow. Upon hearing that taxi drivers’ grey matter literally enlarges and adapts to create a mental map of the city, taxi driver David Cohen, joke when interviewed by the BBC:

“I never noticed part of my brain growing - it makes you wonder what happened to the rest of it.”

A humorous 1979 film about this learning experience, called The Knowledge, was written by Jack Rosenthal for ITV, and was in 2000 voted number 83 in a list of the 100 Greatest British Television Programmes compiled by the British Film Institute. And if you fancy seeing how well you would do at passing ‘the Knowledge’, visit the London Transport Museum and have a go on their version of the infamously tricky test.

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