No it's alright. I don't mean the psychopathic like in ASiP. I do mean the REAL London 'black cab' drivers.

A little bit of History
Horse drawn carriages such as 'hackney' (which incidentally is a London Borough) have operated, for hire, since the 17th Century in London. In 1636 the number of these was set at 50. The first taxi stands (ranks) started in the same year in The Strand (which means 'beach' but that's another story). In the 19th century the heavy, cumbersome hackney carriages were replaced by cabriolets (cabs for short).

In 1875 the 7th Earl of Sheftesbury set up cab shelters for the taxi driver. These are all green and no larger than a horse and cart as they are on the public highway. These provide shelter and hot food and drink for cabbies. They accommodate between 10-13 men. There are seats, tables, books and newspapers. Gambling, drinking alcohol and swearing area forbidden. There are still 16 of these shelters which are all Grade 2 Listed, all of which are in use.
www.london-footprint.co.uk/artcabshelters.htm

Modern hackney carriages (taxis)
These can be flagged down on the street or hired for a taxi rank (mini-cabs cannot be hailed from the street). These are known as 'black cabs' (although other colours are available and they may have adverts all over them). All black cab drivers are licensed and must have passed an extensive training course (the Knowledge). In London there is no limit to the number of black cabs allowed. They operate within a set radius of Charing Cross Station.

The Knowledge
A London black cab driver must be able to decide routes immediately at a passenger's request or altered traffic conditions. The driver should not have to refer to a map, a satnav or ask a controller by radio. In order to enable a driver to do this they have to pass the Knowledge a series of exams which originally started in 1865. It is the World's most demanding course for taxi drivers.

Candidate drivers are required to learn 300 routes or 'runs' of London as referenced by their guidebook the 'Blue Book'. Would-be cabbies follow these routes around London on a motorbike. They must have no criminal record, totally clean drivers licenses. On average it takes 34 months for candidates to pass the Knowledge.

Before they pass the Knowledge candidate drivers have to make a set number (at least 12) of 'appearances' or exams in front of a Public Carriage Officer Examiner. The work that goes into 'chasing the Knowledge' is equivalent to a 3-4 year University Degree.

When the candidate has successfully passed all the 'appearances' they gain their license. The physical formalisation of certification is the 'green badge' which is proudly worn (Jeff wears his badge in ASiP). Their first aim when passed is to save up money to buy their own cab.

The Brain Development of Cabbies

Dr. Eleanor McGuire received a Nobel Prize for Medicine in 2003 for her research into the function of cabbies brains (clearly I am paraphrasing here!). There is strong evidence that the training cabbies undergo measurably alters the hippocampus of trainee cab drivers. (The hippocampus is the area of the brain used for spatial memory and navigation). It is generally larger in taxi drivers than the general population. This does however seem to come at a cost to new memory and learning; specifically associative memory.

www.psychblog.co.uk/the-double-edged-sword-of-the-cabbies-hippocampi--310.html
www.lse.ac.uk/collections/informationSystems/PDF/theses/elauf-calderwood.pdf

There are also some pretty funny, and clever cabbies' blogs to be found. For anyone who's been driven around London will know of their knowledge of the city and also...how shall I put it...their forthright opinions on..well almost anything really!

www.cabbieblog.wordpress.com
www.londoncabby.blogspot.com

Finally, a word of advice. When in London ALWAYS use a licensed taxi! NEVER get in a mini-cab hailed from the street. (Hotels will advise reputable mini-cab firms and will call one for you).