The only way for Gordon Brown to stay in office is if he gives up some of his power. A Cabinet reshuffle in September is almost the only means left to strengthen his faltering position, combined with a recovery plan to alleviate problems in the housing market and rising fuel prices. Such a reshuffle may not be enough, and it will only work if Mr Brown appoints ministers of independent stature. That must include leading Blairites.

Most reshuffles are of more interest to Westminster than to voters, so they are soon forgotten unless they are mishandled like Harold Macmillan’s “Night of the Long Knives” purge of a third of his Cabinet in 1962, which made things worse. The latest Populus poll shows that more than half the public think a significant reshuffle would not help Labour electorally.

Prime ministers in trouble also need to bind in potential successors. In November 1967, after the humiliation of devaluation, Harold Wilson appointed Roy Jenkins as Chancellor. This was a shrewd move by Wilson, who not only took a lower profile but also ensured that his main Cabinet rival had to carry through unpopular spending cuts and tax increases. During 1968 Jenkins was urged to depose Wilson but remained loyal.

In May 1993 John Major replaced Norman Lamont as Chancellor with Kenneth Clarke, visibly a “big beast” with the authority to implement tax rises.

Alistair Darling suffers from being overshadowed by Mr Brown, as well as from economic troubles not of his own making. But his stoic loyalty in the face of Downing Street interference is unlikely to be rewarded except by a transfer.

Mr Brown needs to demonstrate that he is willing to accept powerful ministers around him, rather than just close allies. That should rule out Ed Balls as Chancellor, at least this side of an election. The obvious option would be to swap Mr Darling and David Miliband.

A more radical choice would be to bring back Blairites such as Alan Milburn, John Reid or Charles Clarke (if he has not ruled himself out by his candid criticisms).

A central aim would be to enlist, and neutralise, leading critics. However, for this to work, 10 Downing Street has to intervene less. That would involve a big change of style and approach by Mr Brown. Can he reinvent himself as a leader willing to share power rather than to control? Many Labour MPs believe it is already too late, but that is now his only hope.

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