Britain's supermarkets say they have an unbeatable offer - their quality, convenience and value. But, how do the claims of the retailing barons check out?
Are the big supermarkets too powerful? Are shoppers being charged too much?
As the Office of Fair Trading investigates their profits Panorama examines the supermarkets' methods and asks if we are paying too high a price for their increasing influence over our lives?

(Note: as Panorama is topical and likely to react to events in the news its subject matter may change)