Keeping the bad news about foreign criminals from the Prime Minister for three weeks has only added to the impression that Charles Clarke has been less than candid in his crisis management. As such, Mr Clarke has taken on the air of a released criminal due for deportation — if only we could find him. It is almost inevitable that he will be found out by a recidivist thug, and so it makes sense to engage in a little of the activity that seems to have been absent in the Home Office — planning.

The argument that this department of state has simply become too vast to manage would be regarded as a fairly lame excuse in any multinational corporation. Complex empires are perfectly manageable. True, the Home Office’s attention has frequently been diverted by Downing Street into, for example, headline initiatives on asylum removals and street crime. Yet Downing Street’s attentions were surely a symptom of exasperation at systemic management failure.

There are various ways that the Home Office could be dismantled. The Prison Service, for example, was once an agency. The asylum and immigration service conceivably could be hived off. Yet these areas would still require a minister answerable to parliament when things go wrong. Drugs policy, soon to come under review, potentially could be repositioned as a health issue. But drugs have a significant impact on public order: it is hard to believe that drug crime would not come straight back to a Home Secretary’s door.

The real problem is not that these functions — police, prisons, probation and immigration and nationality — have been lumped together in some überministry. It is that they have remained too separate; fiefdoms failing to provide each other with even the most basic information. A certain amount of slimming down at the Home Office has already taken place or is in train. The issue now is one of properly managing what remains. The first step must be to extract the correct information about, for example, the scale of the asylum backlog and the number of foreigners in British jails. Separating these institutions is not the priority — forcing them to talk to each other is imperative, as is finding managers contemptuous of mediocrity.

Mr Clarke would like to believe that he will remain at the helm, though his Prime Minister knows that one seriously embarrassing incident involving a putative deportee will be the end of him. If Mr Clarke falls, John Hutton is the front-runner to replace him. He could bring the methodical determination that is needed. John Reid, the minister for all seasons, has had more posts than John Prescott has had affairs, but it would be inappropriate to appoint a Scot to a department that, since devolution, has had so many functions hived off in Scotland. David Miliband would be an unusual choice, as a junior minister who is relatively untested. He could do with a pair of spectacles that make him look less boyish.

Best placed to do the deed is Alan Johnson, the Trade and Industry Secretary and a potential prime minister. Now, more than ever, the job of Home Secretary is one that must be done forcefully, intelligently and thoroughly. Politicians rarely leave that job with their reputation enhanced. But should Mr Clarke be departed from the Cabinet, this would be the ultimate test for an aspiring leader.