Whatever this inquiry finds, Mr Blunkett will not easily salvage his reputation

The prurient interest that many in this country take in the private lives of public figures is one of our least attractive national characteristics. Just about everyone in the public eye - from the loftiest politician to the lowliest TV personality - finds themselves subject to intense scrutiny by the media. The Independent takes the view that private lives are just that: private.

It is for this reason that, until now, we have refrained from reporting on the relationship between David Blunkett, the Home Secretary, and Kimberly Quinn, the publisher of The Spectator magazine - reports on which have been surfacing in the press for some months now. We do not consider revelations about a politician's sex life, even of a figure as senior as Mr Blunkett, to be intrinsically in the public interest.

However, serious accusations have been levelled against Mr Blunkett, to the effect that he abused his position as Home Secretary as a result of his relationship with Mrs Quinn. It has been alleged that Mr Blunkett fast-tracked a visa application for Mrs Quinn's Filipina nanny, an act that would constitute a gross abuse of his position as a government minister. The fact that Mr Blunkett, whose portfolio includes immigration, would be well-placed to intervene on a particular individual's behalf makes the charge all the more serious. This affair has moved out of the private and into the political sphere. The accusations that Mr Blunkett also allowed Mrs Quinn to use his government chauffeur, and security services, although less serious, add to the picture of a man who let his relationship cloud his judgement.

Mr Blunkett's spokesman has argued that the extent of the Home Secretary's involvement in the visa application was, on the behest of Mrs Quinn, to look over the application form and check it was "in good order". It all comes down to Mr Blunkett's word against Mrs Quinn's. It is therefore entirely proper that an inquiry will be established to discover the truth and determine whether there was any undue interference from Mr Blunkett.

Even if the Home Secretary is proved innocent, there are already some inescapable ironies in this affair. One of the most right-wing and populist home secretaries of recent times is being pursued relentlessly by the right-wing, populist press. A politician who attempted to portray himself as "tough" on immigration is now suspected of bending his own rules to make it easier for someone from abroad to take up permanent residence in Britain. Mr Blunkett is beginning to resemble someone who has been hoist by his own petard.

If the Home Secretary is found to have misused his position, he can surely not continue in his post. Peter Mandelson, the former secretary of state for trade and industry (and now Britain's European commissioner), was forced to resign when he was perceived to have used his influence to help foreign nationals to acquire a passport. If found culpable, it would be difficult to see Mr Blunkett avoiding the same fate.

And there is a question-mark over the Home Secretary's judgement regardless of the truth of these allegations. One of the unwritten rules of politics is that when a minister becomes an intense focus for public opprobrium - no matter how unjustly - they cannot continue in their post. While many will sympathise with the pain caused to both parties by such a bitter break-up, Mr Blunkett is at serious risk of becoming just such a liability to the Government. If the rumours are true that he has privately briefed the press himself about his relationship with Mrs Quinn, his judgement is badly distorted.

This storm has broken over a minister who controls perhaps the most sensitive portfolio in the Cabinet. The Queen's Speech last week made it clear security would be the major theme of the Government's legislative programme. Mr Blunkett's illiberal ID card scheme will soon begin its passage through Parliament. When we ought to be embarking on a detailed study of Mr Blunkett's policies, we find ourselves in the unhappy position of being forced to examine the character of the Home Secretary himself.