You emerge from Leicester Square tube station, blinking in the London sunlight (optimistic, but some days in London it doesn’t rain). First stop, a mission not just for pints or a G&T, but for a journey through time to a small and modest watering hole, the Tom Cribb. It is one of London's most storied pubs, a homage to the relentlessly harsh 19th century sport of bare-knuckle boxing.