We sent a reporter to test the claim at Wiltons in the West End, where a three-course a la carte lunch for two with wine came to £245.36.
Valentine Low and his wife Eliza had a glass of champagne and a medium priced bottle of wine (£44) with their Dover sole. He said the meal was "memorable" - for the staggering cost.
However, leading restaurant owners insisted London was not a rip-off and said profit margins were under intense pressure.
Michel Roux Jr, owner/chef of Le Gavroche in Mayfair, said: "If you compare two- and three-starred restaurants in London and Paris you'll find Paris is double the price. For example, in one three-starred restaurant in Paris recently they were charging £70 for a slice of turbot. I charge £40."
Rose Gray, co-owner of the River Café in Hammersmith, said: "London comes out as the most expensive overall because there is an incredible number of good quality restaurants, bringing the average price up. The best comes at a price."
Chris Galvin, of Galvin At Windows in Park Lane, blamed the cost of administration and Michael Gottlieb, managing director of the Christopher's group, said London restaurateurs had to pay a higher proportion of their profits to landlords.