Don’t be fooled by the unexpected rise in retail sales last month. Consumers have run out of puff and will soon collapse in a heap. The wild swing from a sharp fall in spending in June - revised down to 4.3 per cent – to a 0.8 per cent increase in July left some economists baffled.

The rise in volumes came despite an average 1.6 per cent increase in prices, driven by a 6.2 per cent surge in the cost of food, the sharpest gain since 1992.

The Bank of England has noted that the erratic movement in retail sales has made it hard to judge the underlying trend in spending.

But retail bosses are convinced they know what the trend is - down. The head of one of the country’s biggest retailers told me yesterday that the jump in July was largely the result of shops shifting stock they wanted to get rid of with discounts - the rise came predominantly in nonfood products, particularly clothing.

He predicted that shoppers would be in a grim mood after returning from holiday and that this would be reflected in the September figures.

Away from the aggregate figures, the signs of strain are very clear. Asda, the country’s second-biggest supermarket chain, reports increasing weakness in spending towards the end of each month, as shoppers struggle to make it through to next payday.

This strain is helping those retailers such as Asda and Wm Morrison that have a reputation for keen prices. The discount chains are doing even better, with the likes of Lidl and Aldi, which have struggled for years to make big inroads in the UK, experiencing a surge in sales.

Iceland, the frozen food group, is also making hay. Frozen food sales generally are strong partly because shoppers believe there is less waste than with fresh produce.

By contrast, those chains that focus on upmarket fresh food, notably Marks & Spencer, are having a tough time. As for shops focused on homewares and DIY products . . . well, don’t ask.

Retailers fear another lurch down in sentiment after Christmas and are steeling themselves for a truly grim 2009.

Leading forecasters are predicting that consumer spending will fall next year, after growing by an average of more than 3 per cent a year since 1997.

This rising tide made life easy for retailers. In these tougher times it is becoming clearer who was good and who was lucky. And the gap will only widen from here.

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