To become a cab driver in London you have to do "The Knowledge"

The 'Knowledge of London' examinations were introduced in 1851 following the Great Exhibition in Hyde Park, when drivers had been severely criticised for not knowing their way around. Initially only main roads between major points in the capital needed to be known. Today, "All London" Green Badge holders require a detailed knowledge of the 25,000 streets within a six mile radius of Charing Cross, with a more general knowledge of the major arterial routes throughout the rest of London. Any taxi driver working in central London or Heathrow Airport requires an "All London" Licence. Alternatively, cabbies can be licensed for one or more of the 16 suburban sectors outside of the city centre.

The Public Carriage Office checks would-be cabbies for any criminal record before giving him or her a list of 400 runs to learn, known as The Blue Book.

Prospective cabbies then spend 18 to 36 months touring the streets of London in all weather on their scooters. They must learn the location of 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 addition, drivers must be able to take passengers from one location to another via the most direct route.

After frequent interviews at the carriage office where examiners test them on The Knowledge, they are then tested on the London Suburbs. After this they have to pass an advanced driving test, and on completion of this they are awarded their licence and badge. Poor souls.