Charles Clarke yesterday told Cabinet colleagues that he was attempting to deal with a “systemic failure” that had led to 1,023 foreign national prisoners being released improperly. Even as he spoke, however, it was revealed that 900 present jail inmates are not identified by their nationality and perhaps 600 more claimed falsely to be British. The systemic failure to which the Home Secretary thus referred is so large that the actual size of this appalling mistake is still not known.

Systemic woes cannot absolve ministers of their responsibilities. If any of those released without being duly considered for deportation are found to have committed serious crimes subsequently, Mr Clarke will appreciate that his credibility would be shredded. The broader obligation that he has, for now, is to ensure that there is a systemic solution produced for the Home Office — and not just a short-term fix that allows this affair to be brought to an end, but at the price of a displacement effect which means that different embarrassments will emerge later. The Home Office as it is currently constituted is simply not capable of commanding sufficient public confidence.

There are plenty of suggestions for reorganisation. The most fundamental, endorsed by David Cameron, for the Conservatives, and Lord Ramsbotham, the former Chief Inspector of Prisons, would bring the creation of a new, separated, Department for Homeland Security on the US model and a Home Office focused on law and order.

This is an idea that should remain in the frame, but there are difficulties with it. The American analogy is not perfect. There was no real equivalent of the Home Office in the US before 9/11, but America did have an array of independent and semi-autonomous agencies that did not communicate with each other. There are already those in Washington who think, partly because of the patchy response to Hurricane Katrina last year, that the department itself has become a bureaucratic monster. It is not clear that security/terrorism and conventional crime can invariably be treated in isolation: experience in Northern Ireland would suggest the opposite. An alternative approach may have merit.

It would start with completing the task of slimming down the functions of the Home Office. A number have already been dispersed to the Department for Culture, Media and Sport, the Department for Constitutional Affairs and the Office of the Deputy Prime Minister. There are others that might be dispatched as well. The transfer of its remaining role in the judicial system is sensible. It is not obvious why Mr Clarke is in charge of “communities and volunteering”, or of “ equality and diversity”, let alone the supervision of animal testing. His principal purpose should be to serve as the Secretary of State for Crime Prevention.

To do that, though, the main agencies of the Home Office — involving the police, prisons, immigration and nationality and the Probation Service have to accept a new approach to their management. These are often sizeable organisations that have developed cultures which have tended towards insularity and where it has proved hard to insert more than a token sprinkle of outside figures into the highest levels of administration.

The official statistics released yesterday show that crime, particularly violent crime, remains far too high. The Home Office needs to lose weight and to prepare itself for a different race.