David Cameron’s much rumoured Shadow Cabinet reshuffle will have no bearing on Conservative prospects at the next election. That is true of most reshuffles, which involve moving around politicians unknown to most voters. There is no evidence either of any improvement in departmental performance, or of much impact on the polls.

There are only rare exceptions: notably the return of Lord Mandelson. Not only did he end the feud between the Brown camp and the Blairites, but he is also a political heavyweight.

Now the Tories are considering whether to play their own Mandelson card with the return of Kenneth Clarke, possibly as Shadow Business Secretary. But he would never confront Mr Mandelson in person as they sit in different Houses. I do not see what benefit Mr Cameron would gain from having him back in the Shadow Cabinet, as opposed to his current role heading the democracy task force defending Parliament, and perhaps the occasional frontbench apparance in big debates.

Mr Clarke can gain public attention. But there are risks in his outspokenness. The problem is not the euro, which Mr Clarke accepts will remain a dormant issue until the election, but, rather, the Lisbon treaty, which he favours. That could be explosive, especially if the Irish vote in favour this autumn.

The fevered debate about Mr Clarke on the blogosphere reflects a deeper Tory ailment: a neurotic short-termism fuelled by overinterpreting the latest events or polls. I am a fan of the Tory websites, which carry stories not reported elsewhere. But bloggers feed a frenetic mood that militates against long-term thinking. Another result has been a flood of statements and initiatives by party spokesmen.

But these stories make no impact on voters. Ups and downs in the polls will be determined by views on the economy, not opposition initiatives. The Tories need to react and say less, and think more. Their priority is to develop a credible strategy for what is likely to be a dire fiscal inheritance.

A Shadow Cabinet reshuffle, with or without a big beast, will be largely irrelevant.

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