A surprise jump in high street sales last month today fuelled uncertainty over the true state of consumer spending as Britain’s economic woes deepen.

The quantity of goods sold by retailers last month unexpectedly leapt by 0.8 per cent, even as shop prices rose at their fastest pace in a decade, official figures indicated.

The stronger-than-expected trading conditions suggested by the data confounded City predictions that sales would drop by a further 0.3 per cent, after a 4.3 per cent plunge in June. The figures further muddied the picture over the scale and speed of a widely anticipated consumer downturn.

Sales growth was broadly based, with household goods, clothing and footwear and a wide category of other stores all reporting strong rises on the month.

The rise in sales volumes came despite an average 1.6 per cent increase in prices, the steepest since May 1998, which was driven by a 6.2 per cent surge in the cost of food — the sharpest gain since March 1992.

The strength of the official figures from the Office for National Statistics is bound to draw scepticism in the City. The ONS retail sales data has been volatile in recent months, with a record rise in sales volumes in May followed by June’s record decline.

June’s sales fall was revised today to an even steeper 4.3 per cent, so that this month’s reported rise will be seen as reflecting a recovery to some extent from that precipitous drop.

Despite that explanation, City economists will contrast the stronger official numbers with a brace of bleak surveys of last month’s high street trading conditions from the British Retail Consortium (BRC) and the CBI.

The CBI’s survey last month said trading was at its worst level in a quarter of a century, with 61 per cent of retailers questioned reporting that sales in the first half of July were down compared with a year earlier, against just 25 per cent which reported an increase.

At the same time, the BRC said that unpredictable weather had combined with the housing market’s woes to deepen retailers’ plight as consumers retreated from the shops.

On the BRC’s figures, like-for-like sales, which strip out changes in retailers’ floorspace, fell last month by 0.9 per cent compared with levels of a year earlier.

Today’s official figures will sow doubt over the exact scale of any emerging downturn in consumer demand. Economists expect consumer spending to wilt in the face of a rising burden on families from the soaring cost of living, rising mortgage bills, slumping house prices and modest pay deals.

Leading forecasters have predicted that consumer spending is set to fall next year, after rising by an average of more than 3 per cent a year over a decade-long national spending spree since 1997.

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