In order for a prospective taxi driver to obtain a license to operate a black cab in London, they must first complete a course of study known as The Knowledge the purpose of which is for them to demonstrate that they know the roads, routes and places of London.
The Knowledge, consists of 320 routes through central London, and significant places along those routes including streets, squares, clubs, hospitals, hotels, theatres, government and public buildings, railway stations, police stations, courts, diplomatic buildings, important places of worship, cemeteries, crematoria, parks and open spaces, sports and leisure centres, places of learning, restaurants and historic buildings. In all some 25,000 streets within a six mile radius of Charing Cross are covered along with the major arterial routes throughout the rest of London. The 320 routes are contained within the "Blue Book", officially known as the "Guide to Learning the Knowledge of London", which is produced by the Public Carriage Office, which regulates licensed taxis in London. It is the most demanding course of study required by any taxi regulator in the world. On average two years preparation are required before an applicant is considered ready to obtain a license.
During their period of training, would-be cabbies drive usually ride around London on these routes on a moped which earns them the name of knowledge boys (or girls). A humourous film about this learning experience, called The Knowledge, was written by Jack Rosenthal for ITV.
In order to pass The Knowledge an applicant must first pass a written test, which qualifies them to make an "appearance". At each appearance the applicant faces an oral examination where they must repeat from memory a number of the routes contained within the "Blue Book" as requested by the examiner. Whether an applicant has passed "the knowledge" or not is purely at the discretion of the examiner. It is extremely rare for a driver to reach the required standard in fewer than 10 appearances.
There is some evidence that doing The Knowledge can results in measurable physical changes in the brain of a potential cab driver[1].
