Eaton Square is an improbable base from which to launch a revolution. The slick, clotted-cream terraces of one of Belgravia's most expensive addresses exude undisturbed privilege. Yet in a basement of one of the elegantly proportioned houses, marked only by a neatly stencilled sign to the tradesmen's entrance, lies perhaps London's closest equivalent to a Silicon Valley garage.

It takes a little while, walking along a corridor past the small, dark offices, to realise that its location is not the most unusual aspect of this start-up's cluttered premises. On the walls hang frame after frame of the distinctive paintings of Paula Rego and Martin Maloney. The art and the basement belong to Charles Saatchi, ad-man-turned-household-name art collector who lives upstairs with Nigella Lawson, whose innocently lubricious cookery programmes have earned her equal fame.