Construction output fell a further 2.4% in the first quarter of this year, according to estimates plugged into the official data used to calculate the UK gross domestic product.

The figures for total output of the UK economy in the first quarter show a disturbing fall of 1.9%, with construction a major contributor.

But a closer look at estimates for construction activity reveals that the ONS statisticians’ original estimates for last year have been heavily revised downward.

In rough and ready terms the industry did £6 billion less than originally thought and when this is added into the mix it helped pull down the official figure for total UK gross domestic product for 2008. (Here’s a link to the previous set of GDP figures for reference.)

This brings the figures used in the GDP calculation closer in line with the official construction output figures, which in fairness are calculated slightly differently.

The latest figures do suggest a further fall of 2.4% in construction output, which if mirrored in the official construction output data would mean that industry activity is down more than 10% from peak.

But when the dust settles this figure may well be an underestimate of the damage done to construction, as estimated figures tend to be revised down on the downswing and up on the upswing.

So be prepared for some nasty numbers when we see the official figures in June.

Certainly, from the chats I have had following the release of Budget 2009 figures with people who have their fingers on the pulse there is a growing view that even the most pessimistic forecasts are now looking realistic.

But just as the chirpiness generated by the recent spring torrent of positive reports should have been treated with a degree of scepticism, the depression following the bucketful of bad news in the Budget should not be overplayed.

It’s bad, but then again we knew that.