Prunella does it for Tesco

Fawlty Towers actress Prunella Scales' portrait of a battleaxe customer in adverts for Tesco earned the chain £2.2billion in extra sales, it emerged yesterday.

By contrast, her on-screen husband John Cleese's TV campaign for Sainsbury's was a flop. However, Sainsbury's reaped £1.12billion by using Jamie Oliver in its ads, while Vic Reeves and Bob Mortimer netted £223million for First Direct, according to advertising guru Hamish Pringle.

His new book, Celebrity Sales, compares sales before and after campaigns, linking results to how the public respond to stars. Celebrities in ads need an engaging yet understated manner, he believes.