You can hail a Black Cab in London by stepping off the kerb in front of one with your right hand raised. Do not attempt this if the little yellow light is not on. Black Cabs are a font of useless information on wheels. Anything you want to know, or probably would rather not, can be discovered during a journey in one of these vehicles.

They are operated by incredibly cheerful, yet strange looking men (and very, very occasionally, strange looking women) who tell you, by way of introduction, that the 'rahd's gawn mayd'¹ today. They speak in a mixture of clichés and a dialect called Cockney Rhyming Slang and deliver gems from what they call 'The Knowledge'. This usually involves reactionary commentary on current news events mixed with some very colourful abuse hurled at motorists and pedestrians alike.

History

The Black Cabs' history goes back to the time of horse-drawn cabs which were called Hackney Cabs. The term comes from the French word haquenee referring to the ambling horses used to pull the original Hackney Carriages². The Hackney Carriage originated in London, England in 1625. The cabs still come under some of the old rules from the horse-drawn days.

The Black Cabs are the only taxis that are allowed to pick people up from the street. There are also mini cabs in London, however they can only collect someone if they have made a prior arrangement by phone.

Before a taxi driver gets his Hackney Cab Licence he or she must pass a test called 'The Knowledge'. This is a difficult test and requires the cabbie to know the streets of central London like the palm of their hand. Mini cab drivers do not need to pass this test.

The Knowledge

Taxi drivers in London undergo a demanding and arduous testing of their knowledge of the city, its daily traffic patterns and the fastest routes between locations. Estimates suggest that gathering the basic understanding needed to acquire The Knowledge involves a full-time year of study, absorbing the information provided by street maps and travelling around the city itself. The result is that drivers of official London Hackney Cabs are renowned for their detailed and intimate knowledge of London's streets and attractions. Strangely enough, scientific study³ has shown that possession and expansion of The Knowledge increases the size of the anterior and posterior hippocampi of the brain - the area that handles spatial memory and spatial navigation. Compared with baseline controls and inexperienced cabbies, long-serving taxi drivers possessed considerable more developed hippocampi.

Models

Today, Hackney cabs number some 19,000 plus in London alone, with many thousands more scattered throughout the United Kingdom. The cabs are usually black, but there are significant variations based on company or advertising requirements. In London there are only three models of cab accepted:

• The Fairway
• The Metrocab
• The Asquith

Licensing authorities outside London also approve taxi designs, but these are unlikely to appear on the streets of London as they have thus far failed to meet what seems to be the hardest requirement - a 25-foot turning circle.

Since January 2000, all Hackney cabs have to be wheelchair accessible. Originally, all Hackney cabs had to be able to accommodate a man wearing a top hat.

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¹ This is the 'road's gone mad' said in an extreme East End London accent.
² The last horse-drawn taxi license was issued in 1946 and was surrendered the following year.
³ The study was published by the University College London in Spring 2000.