Posh Food

Can anyone help me? I need to find some more private dining options for work events. We usually use the Savoy, Pied a Terre, Gauthier, Roux at the Landau and Hibiscus. We need some more options.
It should be fine dining (michelin star preferable) with a private dining room and single table large enough for about 14 guests. Options need to be in Central London.
Anyone? Thanx in advance.

the gherkin