When Alistair Darling said that Britain’s economic conditions were “arguably the worst they have been for 60 years”, the initial reaction from the Opposition and media was either to compliment the Chancellor for his “frankness” or to gloat about the way he had “let the cat out of the bag” and thereby embarrassed Gordon Brown.

This was understandable, because Mr Darling is indeed an unusually straightforward politician, respected and liked by journalists and politicians across the political spectrum. On closer inspection, the Chancellor’s reputation for frankness makes his political blunder worse, since it reveals a flaw more serious than deviousness: basic ignorance of economic facts and figures. This is a failing that the minister responsible for national finances can never live down.

Were there any interpretation of Mr Darling’s comments that tallied with either economic statistics or the realities of British life – or if the Treasury had rushed out a correction, explaining that he had been misquoted or hadn’t meant what he said – this episode might have been forgotten as just another stumble by an accident-prone Government. But sadly for Mr Darling, though luckily for the British economy, there is no way of massaging the facts and figures to make his statement even half-right.

The most obvious contrasts – today’s 5 per cent inflation and 5.4 per cent unemployment may feel uncomfortable, but these are just tiny ripples compared with the tidal waves of economic hardship – the 27 per cent inflation and 12 per cent unemployment – that hit Britain in the 1970s and 1980s.

A similar conclusion comes from almost any other economic indicator: gross domestic product, personal incomes, government finances, employment growth, repossessions. Only house prices are falling faster than ever before – because they were far higher when this downturn began. And despite all the headlines about a credit crunch, financial conditions are also relatively benign. Homeowners and estate agents may complain about a “mortgage crisis”, because banks charge over 6 per cent for a mortgage and require a 10 per cent deposit from first-time buyers, but in the 1970s and 1980s, mortgage rates repeatedly reached 15 per cent and borrowers typically had to save up deposits of 25 per cent or more.

Social and political conditions are now incomparably better than they were 30 years ago. This can be attested by anyone who recalls the three-day weeks and winters of discontent, the petrol rationing and power cuts, the dole queues and miners’ strikes, the credit squeezes and currency restrictions of those days. And other social indicators – child poverty, life expectancy, housing conditions, educational qualifications, pension levels, living standards relative to other countries – are almost all far better today than they were in the 1970s and 1980s, despite the understandable feeling that many of these conditions should be much better, considering the huge tax burdens successive governments have imposed.

What on earth, then, was Mr Darling talking about when he described the present economic crisis as the worst since 1948? The Treasury lamely suggested over the weekend that the Chancellor was not really referring to Britain, but to the world economy as a whole. This “clarification”, however, does not get Mr Darling off the hook. The US has not yet suffered a recession – much less the once in a lifetime depression predicted widely a few months ago – and only last Friday announced a stark upgrade in its GDP figures.

The European economy is slowing and it may well sink into a mild recession – but, this has not happened yet. Developing countries are still growing strongly and even the global banking system, despite all the hysteria, has so far suffered smaller losses in relation to its total capital than it did in the Third World debt crisis of the 1980s.

In short, it is literally impossible to tally Mr Darling’s comments with anything that has happened to the British and international economies so far. Could it be, however, that he meant to offer a forecast? Predictions are, by their nature, a matter of opinion, which means that Mr Darling’s comments, if they refer to the future, cannot be refuted by objective statistical evidence even though there is now no respectable economic model pointing to anything like the apocalyptic conditions Mr Darling described.

Suppose, then, that the Treasury decides to spin his comments not as a description of what has already happened but as a prediction that Britain will suffer its worst economic crisis since 1948 in the year or two ahead. If this was what Mr Darling meant, will anybody believe any economic forecast he presents in his next Budget if this is less than catastrophic? And if Mr Darling does present a catastrophic forecast in a preelection Budget, what will this do to Gordon Brown’s chances of survival? These questions can yield only one answer: the next Budget will be presented by a new chancellor.

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