The Knowledge of London:
All licensed taxi drivers in London must have an in depth knowledge of the road network and places of interest in the Capital. This is known as ‘the Knowledge of London’.
For would be, All London taxi drivers, (Green Badge) this means that they need to have a detailed knowledge of London within a six mile radius of Charing Cross. Suburban Taxi drivers (Yellow Badge) need to have a similarly detailed knowledge of their chosen sector.
The basis for learning the Knowledge is the 'Guide to Learning the Knowledge of London' (the 'Blue Book') which contains lists of routes (or 'runs'). Applicants need to learn these routes and they also need to know all the places of interest and important landmarks on the route and around the start and finish points. There are 320 runs for All London applicants to learn and between 30 and 51 for suburban applicants (depending on the size of the sector).
Before starting to learn the Knowledge, applicants are invited to attend the PCO for an introductory talk. Here they are given a copy of the Blue Book plus advice on how to learn the Knowledge.
When applicants have learnt all the runs they can attend the PCO to be examined on their Knowledge. After a basic written examination applicants are tested by one-to-one interviews (called 'appearances') where they are given the start and finish points of imaginary taxi journeys and have to describe the shortest route between them. A detailed description of the Knowledge of London examination system is available
On average it takes an All London applicant 34 months to learn the Knowledge and pass through the examination process, 26 months for a suburban applicant