Asif tugs at his right cheek as he ponders how to navigate from Holloway Road Station to the Quality Chop House, two miles away on Farringdon Road. A dozen fellow students of the Knowledge of London, the gruelling qualification required to drive one of the capital’s famous black taxis, watch him squirm under the instructor’s classroom interrogation, with another dozen listening in via a video call. Eventually he concedes defeat and rejoins the onlooking semicircle.