It is as well for Gordon Brown that everything is relative. Consider how damaging yesterday's disclosure about the details of three million driving theory test candidates having gone missing would have been for the Prime Minister and his government had it not been for the earlier revelation about the loss of 25m people's particulars by HM Revenue and Customs (HMRC). Yesterday's Commons statement by Ruth Kelly, the Transport Secretary, does not constitute an improvement. Only an unbalanced optimist would think so. Mr Brown does not fall into that category. Indeed, the gloom enveloping him since the humiliation of the election that never was must have darkened with the latest disclosure.

It is as well for Gordon Brown that everything is relative. Consider how damaging yesterday's disclosure about the details of three million driving theory test candidates having gone missing would have been for the Prime Minister and his government had it not been for the earlier revelation about the loss of 25m people's particulars by HM Revenue and Customs (HMRC). Yesterday's Commons statement by Ruth Kelly, the Transport Secretary, does not constitute an improvement. Only an unbalanced optimist would think so. Mr Brown does not fall into that category. Indeed, the gloom enveloping him since the humiliation of the election that never was must have darkened with the latest disclosure.

True, it is not in the same league as the HMRC blunder. Unlike that case, no bank account details, National Insurance numbers, driving licence numbers or dates of birth have gone missing with the hard-disk drive that did not turn up in the security facility in Iowa City in the US of Pearson Vue, a global electronic testing business working for the Driving Standards Agency. For a company that prides itself in offering stringent security policies and "innovative computer-based testing solutions through secure, electronic test delivery", the loss of the disk is embarrassing and damaging.

It is acutely embarrassing for the government as the announcement came on the very day Alistair Darling, the Chancellor, sought to reassure the Commons and the country at large that Labour was getting to grips with data protection. This message was to be founded, first, on yesterday's interim report of the businessman, Kieran Poynter, into the HMRC bungle which set out security measures to prevent such an incident occurring again; and, secondly, on the blueprint of Sir Gus O'Donnell, the Cabinet Secretary, for the handling of sensitive information across the government.

Instead of yesterday's statements making matters look better for ministers, they ended up making matters appear worse. For the Opposition, the situation must have been akin to being presented with a barrel-load of fish and a loaded gun. What caused the government greater damage was ministers making an easy target of themselves on the very day they had planned to pull themselves out of the sticky stuff. It was not clever on several counts. The touch, judgment and competence of Mr Brown and his Cabinet were once more called into question.

The government's credibility has taken another knock. It has instructed the private and public sectors to abide by the Data Protection Act but has been involved in breaking it (albeit inadvertently) in different ways. It should set its own house in order before telling others to.

Questions remain about this latest announcement. Ministers were told in May that the disk had gone missing. Why has news of it emerged only now? Did ministers hope it would be overshadowed by the Poynter and O'Donnell initiatives? That would have been naive in the extreme. The risks to the public of fraud are, fortunately, lower than in the HMRC case. The damage to a government that cannot get itself off the ropes is considerable.