The price of our basket of dairy items recorded its biggest rise since the survey began on 4 January, 2005. It is now 7.2%

more expensive than ten weeks ago, following its third consecutive rise, returning to roughly the same level as it was one year ago. But it remains 4.9% cheaper than when the survey was launched.

Pre-packed, own-label Blue Stilton provided the basket's biggest price change, rising 18.4%. After five consecutive falls in the price of Blue Stilton from March 2005 to March 2006, the price has risen in the past three surveys.

Stilton Cheese Makers' Association secretary Nigel White said that he believed the earlier falls in price had been driven by competition among the multiples to be the cheapest.

"It was simply throwing money away, because a price drop doesn't do anything for volume, it just sucks margin out of the chain. This has been borne out by the fact that volumes have been quite good recently despite the price increases.

"Price is a very blunt instrument and should be a weapon of last resort. The money would be better used in improved packaging or labelling or on promotions that work, such as ­in-store sampling or recipe ideas."

Large free-range eggs also increased in price, gaining 5.3% since the last survey, which more than reverses recent cuts.

British Free Range Egg Producers Association vice chairman John Widdowson said that he welcomed the increase, but added: "The initial enthusiasm has turned to disappointment as producers haven't seen any more money.

"Producer prices have been at a low level for 18 months, and now that prices have increased, the retailers have held on to most of that, which is unacceptable. They are making huge profits while our members are losing money. The looming problem will be a shortage of free-range eggs. Demand is growing but there isn't any reinvestment taking place, due to a lack of confidence."