Phil Hannah

London's black cab drivers are required to pass one of the most demanding qualification tests in the world, known as The Knowledge, which has changed little since its introduction in 1865. ​ The test requires candidates to memorise 320 standard routes through central London, covering some 25,000 streets within a six-mile radius of Charing Cross, along with thousands of points of interest within half a mile of each route. ​ During training, would-be drivers, known as Knowledge boys and girls, typically follow the routes on a motor scooter with a clipboard fixed to the handlebars, displaying the streets to be learned that day. ​ At the examination, candidates must identify two points of interest chosen by their examiner, then recite the shortest route between them from memory, naming every road, junction, turn, and landmark along the way. ​ The full qualification typically takes three to four years to complete, with candidates required to pass at least twelve one-on-one oral examinations throughout the process. ​ Research has found that training for The Knowledge can measurably alter the hippocampus, the part of the brain responsible for spatial memory, which is generally larger in London taxi drivers than in the wider population. ​ There are two licence badges upon qualification: a yellow one covering the suburban areas, and the considerably more difficult green badge, which covers all of London. © All About Britain #drthehistories