TRADING in the retail sector has become a valuable indicator of how an economy is doing.

It may not be the most rigorous research, but generally, if shops are busy, there’s an air of optimism.

If shops close, are boarded up and customers disappear, things are less good.

Consider the way the success of Liverpool One has been seen as an indication of resurgent Liverpool.

Step forward to the Radio 4 microphone the soon to retire Tesco chief executive, Sir Terry Leahy, who yesterday was talking about the supermarket chain’s half-year results.

His view, of course, is a little wider than Liverpool.

Under his tenure, he has overseen the firm’s global expansion. Being Britain’s biggest retailer is one thing. Taking on markets in the US and Asia is another, but it’s clearly been a challenge Sir Terry has relished.

Yesterday, the firm reported half-year pre-tax profits of £1.6bn. The figure, for the six months to August 28, was up 12.5% on the same period a year earlier.

The company said UK sales growth was “modest” – citing low food price inflation and higher fuel costs, that resulted in customers spending more at the pump instead of in store.

Tesco is the world’s third largest retailer. The firm’s Asian markets were “emerging strongly” from recession, with profits rising 30%, according to yesterday’s update.

In the UK, economic recovery was slow, Sir Terry said, but added it had coped well with “subdued demand”.

Sir Terry’s comments onŠ Tesco’s performance in the US were of particular interest.Š

He described this as a very well established, mature and complex market, adding that, to make a mark in such conditions, firms had to invest heavily and brace themselves for losses over a long period of time. The mostŠ surprising disclosure was that some newly-built Tesco stores in the Western US lie mothballed – no stock, skeleton staff, no customers. These ghost stores had been built to serve new housing developments.

Instead, these properties, like the shops built to serve them, lie empty. A stark and chilling reminder of the extent of the dip in the US economy – and a reminder perhaps that the UK has fared a little less badly than our North American cousins.