"If Le Gavroche banned smoking, yawn. But the fact that a mainly young person's restaurant is doing so is extremely interesting. There are very few quality restaurants in London with bans, so this will be watched very closely by everyone else. Zuma's initiative is very brave." Harden's surveys have found smoke is one of diners' biggest gripes - despite the fact that only about one per cent of restaurants, including Rules in Covent Garden, Burnt Chair in Richmond and Marylebone's the Providores, are smoke-free.