Errors deal fresh blow to a battered credibility

The scale of yesterday's revisions is a fresh blow to the credibility of the Government's statistics services, which have been bedevilled by a string of problems.

Most have focused on the Office for National Statistics, led by Len Cook. The latest census figures are reckoned to underestimate the growth in the UK populationby up to a million. Some councils have complained they will suffer cuts in government funding as a result.

From October, the ONS will change the way it estimates retail sales in light of violent fluctuations in monthly statistics. Imports were under-reported by £11bn last year and £22bn over the past four years due to fraud of mobile phone and computer chip. These figures are supplied by Customs & Excise.

The Tories unearthed a double-counting of Britons' pension contributions that they said left a £10bn black hole in the figures. The worst hitch was in 1998, before Mr Cook took over, when the ONS had to suspend its estimates on average earnings figures because of concerns at the Bank of England.

The ONS said GDP revision was due to problems with estimates of construction output supplied by the Department of Trade and Industry.