A London black cab licence goes only to drivers who pass the Knowledge. Candidates learn every street within six miles of Charing Cross, which takes most of them three or four years. Transport for London (TfL) then licenses only a quarter to a third as many drivers each year as apply.
The prize is the green badge, which lets a driver work anywhere in Greater London.
What the Knowledge asks
A trainee, known as a Knowledge Boy or occasionally a Girl, covers around 20,000 miles by moped inside that six-mile circle. They learn around 25,000 streets and thousands of points of interest, from hotels to monuments.
There is no single exam. Candidates face a series of “appearances”, reciting the most direct route between any two points until the examiners are satisfied. One Guardian writer who qualified in 2012 needed 19 appearances over 18 months, and said many need more.
Older examiners were harsher. John Mason, TfL’s head of taxi and private hire, recalled one who set a chair facing the wrong way and failed any student who turned it round. Mason said TfL now aims to make the test efficient, fair and transparent.
Why TfL keeps it
Mason’s argument is about the kerb. A hailed cab should set off in the right direction before the driver has fully grasped the destination. Without the Knowledge, he said, drivers typing postcodes at the roadside would hold up buses across the city.
Does sat-nav beat it?
The BBC once raced a black cab against a minicab using sat-nav, from Marylebone High Street to Nunhead, 8.2 miles in the evening rush. The cab driver, Bill, had passed the Knowledge after two years and made it in 42 minutes. The minicab’s sat-nav sent its driver into a bus depot, and he took 53 minutes.
The minicab was cheaper, though. It cost £19 against the black cab’s £35.
Bob Oddy of the Licensed Taxi Drivers’ Association said cabbies had won every one of about a dozen such trials his group had seen. John Griffin, founder of the minicab firm Addison Lee, answered that a cabbie might know 8,000 routes while a sat-nav knows 80,000.
The workforce is changing as well. In 2012, 93% of black cab drivers were white men, but 35% of new Knowledge students the year before were not white.
