The system of hiring young people and working them hard has venerable origins in the City of London. For decades, one route into trading was to be a messenger boy allowed on to the floor of the London Stock Exchange who had to sprint, carrying paperwork between jobbers and the back office, teenage boys known as “blue buttons” because of the badge they wore.

Fast-forward to today and some things have changed and some have stayed the same. The big revolution is in the salary - "blue buttons" were paid £4 10s a week in 1948, according to one oral history in the Institute of Historical Research, as opposed to today's £50,000 base salary plus bonus for junior bankers.