When Abbott Mead Vickers.BBDO won a Silver at the 2002 IPA Effectiveness Awards for its Sainsbury’s Jamie Oliver ads, many financial analysts in the City raised their eyebrows.

Claims that the TV chef had generated more than £1.12bn in the retailer’s incremental revenue in just two years - over half of the £2bn by which Sainsbury’s increased its sales between 2000 and 2002 - and enhanced the group’s “shareholder” value by £1.76bn were met with scepticism. “That’s ridiculous,” said one analyst.