The average price of a Christmas lunch at the big four supermarkets has leapt by more than 10% over the past year, according to exclusive research by The Grocer.

Our findings, based on The Grocer 33, show the average cost of a 10-item festive meal - including turkey, gammon, and all the trimmings - now costs £29.13, £2.67 more than it did 12 months ago.

Prices rose across all the retailers surveyed, but there was a significant difference between the cheapest and the most expensive. Asda, at £27.80, offered the cheapest Yuletide trolley, followed by Morrisons at £28.01, Sainsbury's at £29.92 and, the most expensive, Tesco at £30.94.

The cost of our Christmas meal was pushed up by a big price rise on gammon. The average price of a joint has risen by 24% since last Christmas. Christmas pudding costs 15% more than a year ago, the price of Stilton has jumped by an average of 8% since last December, while turkey prices have gone up 4.6%.

The price of a whole turkey is not monitored by The Grocer 33, so we chose the nearest possible alternative - turkey breast fillets. The fact Christmas dinner costs more than a year ago is unlikely to come as a surprise, with the grocery market now in a period of inflation.

But the extent of the increase is striking - across the board, grocery prices have risen 6% in the past year. And it seems higher prices are unlikely to turn people off cooking for themselves.

According to a survey by The Which? Good Food Guide, 92% of Brits will be cooking and eating their festive dinner at home, or in someone else's home, this Christmas, with just 4% planning to eat out.

The Grocer 33, p20