All Prime Ministers think that a Cabinet reshuffle can give them a short-term boost. It shows that the ultimate weapon, of hiring and firing Ministers, remains in their own hands; it can help with party management, by brining in the loyal and booting out the disloyal. And it can recapture initiative and momentum.
Well, in theory.
The history of these things actually shows many more examples of the nasty and the miserable among reshuffles - and some that have actually been lethal to Prime Ministerial authority.
David Cameron's ongoing reshuffle today is a bit of a shimmy to the Right (his hard-line backbenchers are unhappy), and a bit of flag-waving for his restless 2010 intake of MPs. Getting ride of Kenneth Clarke from Justice is a retrograde step for the old-timer, and for prisons and justice in general, but there you are. His relatively liberal views about crime and punishment are out of favour these days - more's the pity. Bringing in newer MPs might help make the Government seem less rackety and less confused - though the central planks of economic policy put in place by a very unpopular Chancellor will remain.
But in general, these sorts of operations don't help. They make a few headlines for a few days, and then the effect fades. Prime Ministers can be squeamish about sacking people, and Harold Wilson, Margaret Thatcher and Tony Blair all shrank from the task on more than one occasion. Blair wanted to move Gordon Brown in 2001, but just felt that he wasn't powerful enough to do so in the end. Sacking Norman Lamont as Chancellor severely wounded John Major when an angry ex-colleague clobbered him from the backbenches.
The worst example of all was Harold Macmillan (above), another Old Etonian Prime Minister who posed as somewhat more relaxed than he actually was. In 1961 he butchered nearly half of the Cabinet in a desperate attempt to salvage his own political position - and failed utterly, by giving off the whiff of hysterical over-reaction. He was gone within a year of so.
Something else about reshuffles, by the way: they always go wrong. This one has already, because Iain Duncan Smith was supposed to move from Work and Pensions to Justice - but refused.
The simple truth is that this government has lost direction much more quickly than any other of recent times. Compared to (for instance) the 1997-2001 Parliament, key figures such as Steve Hilton and Andy Coulson are gone, and with them a great deal of the creative tension and strategic nous that the Cameron operation wielded in Opposition. None of this rearranging of the deckchairs can change that, and history shows that it might even make things worse. The Prime Minister is now going to have to face a backlash from the sacked, the demoted and the passed-over without such those helpers. It might not be pretty.
