By Mark Easton BBC Home Editor

More than a quarter of Mr Reid's top team are on the move

For the past few days John Reid has been giving a Powerpoint presentation to his top staff.

A picture of an arctic glacier representing a world frozen by Cold War inertia mixes to a slide of white-water rapids with the legend "torrent of new challenges".

First among these challenges is mass migration - 200 million people on the move last year, Mr Reid told the Commons.

Indeed, his government has presided over the biggest ever net migration into Britain - an additional 223,000 people in 2004, and with the arrival of migrant workers from the enlarged EU a figure now probably closer to half a million.

The fact that reform is required to do what one imagines has always been the case must be an indictment of those who have been running the place Reid shakes-up Home Office

The home secretary candidly admitted on Wednesday that, 17 years after the fall of the Berlin Wall, parts of his department are still designed for the Cold War era - a failure in management that Mr Reid believes led directly to the departures of two ministers and a secretary of state.

The civil service assessment that every aspect of the Home Office suffers significant weaknesses, or is cause for serious concern, reflects Mr Reid's view on his arrival in May that the department is "not fit for purpose".

His concerns cover an immigration and asylum system unable even to guess at the numbers of failed asylum seekers and illegal immigrants in Britain, a prison system requiring thousands more cells to house the thousands more foreigners being jailed or deal with those who ought subsequently to be deported.

Wednesday's action plan may lead to the transformation Mr Reid predicts.

All change

Sir Gus O'Donnell, head of the Home Civil Service, conceded that there was "an enormous amount to do" at the Home Office and the department's permanent secretary Sir David Normington told journalists it was "the biggest project" he had ever been involved in.

The title of the plan spells out its purpose in huge letters - to reform the Home Office so it meets the public expectations and delivers its core purpose of protecting the public.

The fact that reform is required to do what one imagines has always been the case must be an indictment of those who have been running the place.

Indeed, 15 directors are being removed from their posts.

But changing some of the personnel and the departmental focus may not be enough to prevent history judging that a central failure of the current government was its inability to plan for the torrent of challenges that a globalised, post-Cold War world presents.