Cabinet reshuffles are at best usually pointless and at worst often destructive. They are usually pointless in that the public’s opinion of a government is unlikely to be altered by them. They are often destructive because ministers who have been in place for long enough to understand a brief are sent off to attempt to master another one. Tony Blair has been consistently and spectacularly inept at reshuffles. This one is, alas, no exception to that rule.

The only argument in favour of holding a reshuffle on the scale that the Prime Minister has done is to introduce lots of fresh blood into a sickly body politic. By that measure, Mr Blair has engaged in a huge amount of displacement activity, but little innovation. There are entrants to the Cabinet, including the able Douglas Alexander, Hazel Blears and, as the Chief Whip, Jacqui Smith, yet they are not in portfolios where they could seize the national imagination. It might be remarked about Mr Blair that, as Nye Bevan said of Harold Macmillan, he has “an absolute genius for putting flamboyant labels on empty luggage”.

Many of the appointments that the Prime Minister has made raise further questions. Charles Clarke acted honourably by insisting that if Mr Blair had lost confidence in him as Home Secretary (although he was expressing it a mere 48 hours ago), it would be wrong for him to assume another senior position. Yet John Prescott is to retain his salary and his title while his department is handed over to Ruth Kelly. It is an astonishing situation.

It is not, though, unique. Jack Straw has been an astute operator at the Foreign and Commonwealth Office. His departure will cause heads to be scratched in Washington and Brussels as well as London. Margaret Beckett is no fool but, equally, she is not a Henry Kissinger. The farce that surrounded the role of Geoff Hoon as a supposed Secretary of State for Europe has compounded matters. John Reid is not without qualifications to serve as Home Secretary, even if his elevation breaks the convention that an MP from a Scottish seat would not hold this office. But the speed at which he has held seven Cabinet slots in the same tally of years is ludicrous. If Sir Thomas More was a man for all seasons, the robust Mr Reid is a man for all reshuffles. He must be permitted a decent stay this time.

And then there is the curious revolving door at the Department for Education and Skills. There was much logic in moving the savvy Alan Johnson to this berth six months ago. To ask him to switch now, with a crucial and controversial schools Bill in its committee stage and a potentially awkward third reading vote to come this month, is strange. To have transferred Ms Smith, Ms Kelly’s de facto deputy, as well borders on the surreal. In the midst of all of these changes, Patricia Hewitt has, bizarrely, been left at the helm of the Department for Health.

The worst aspect of the whole affair is the whiff of factionalism attached to it. Instead of recognising the reality of transition politics and conducting this reshuffle in close co-ordination with Gordon Brown, Mr Blair has left himself open to the suspicion that he is building up Mr Reid and Mr Johnson as rivals to the Chancellor and that he might be willing to soldier on indefinitely to block Mr Brown. Any such strategy is destined to fail, but can do immense damage regardless. This is a corker of a reshuffle even by the Prime Minister’s dubious record: it seems pointless and poisonous.