The Vincent Rooms are the training restaurants of Westminster Kingsway College. They were set up in 1910 by the men who brought French cuisine to London: Salmon, Escoffier and Cesar Ritz. Alumni include Jamie Oliver, Antony Worrall-Thompson and Ainsley Harriott so the school must shoulder some of the blame for the scourge of the celebrity chef.
The current building was designed by that hugely under-rated architect H.S. Goodhart-Rendel and built in 1950-7. Over the door is a slate incised with a picture of a candle-lit dinner for two, complete with champagne and all the implements of high-class seduction, as Kai Lung says. The cat only adds to the decadent atmosphere.
It is signed Ledger, an artist of whom I can discover nothing. It is also said to be a sundial, but there is no gnomon and it faces south-west so the folds of the table cloth that might be placed to tell the time are completely wrongly aligned.