The Knowledge is the in-depth study of London street routes and places of interest that taxicab-drivers must complete to obtain a licence to operate a black cab. It was instigated in 1851, and has changed little since.

It is the world's most demanding training course for taxicab-drivers; and applicants will usually need at least 12 'Appearances' (attempts at the final test), after preparation averaging 34 months, to pass the examination.

When you eat dirt for the first time and leave your family to build a shack in the woods