Delia Smith and Heston Blumenthal are facing up to a tougher future with John Lewis

Celebrity cooks Delia Smith and Heston Blumenthal have helped John Lewis carve out a 28 per cent rise in profits but the pair may have their work cut out as the consumer backdrop turns cool.

The employee-owned department store and supermarket operator yesterday reported group-wide pre-tax profits of 111.2 million in the half-year to 31 July, a rise of 27.8 per cent on a year earlier.

As well as a boost from an advertising campaign featuring the two high-profile chefs, takings were lifted by strong sales of flat-screen televisions, spurred on by the World Cup.

But John Lewis said it was braced for tougher times after figures showed an easing in sales growth for the first six weeks of the second half.

After a resurgent opening half for the department stores, when like-for-like sales surged 12.3 per cent, the partnership said sales have since risen 8.8 per cent. Evidence of a north-south divide in trading has already emerged.

Grocery arm Waitrose shrugged off the food price deflation that has hit many rivals, with same-store sales growth of up to 4.5 per cent in the second quarter.

This has slipped slightly to 3.9 per cent in the second half so far.