The gloom and doom headlines about Gordon Brown’s prospects are premature. Eventually they may turn out to be correct, but a lot still has to happen before he leaves 10 Downing Street.

Mr Brown is obviously in deep trouble: the Glasgow East result was dire and no prime minister or governing party has ever recovered from such low poll ratings to win a subsequent general election. Yet he is not about to be ousted now and, even in September and October, there are still huge uncertainties about the how, when and who, let alone the whether.

Talk of plots is exaggerated. Of course, Labour MPs and ministers are pessimistic; and some are talking to each other about what might happen in the autumn. But that is a long way from forming, let alone agreeing, a coherent plan.

First, the how. Mounting a formal challenge would be cumbersome, requiring the initial support of 70 Labour MPs, and would open wounds very publicly. The media’s favoured option is the so-called greybeards - senior ministers such as Jack Straw, Alistair Darling and Geoff Hoon – telling Mr Brown that it is time to go. So far none of the alleged leaders of a coup has shown any desire to wield the knife. That could happen if there were a protest by Labour MPs after the holidays but, again, there is more talk than signs of action. The option of the family persuading him to stand down has little substance.

Secondly, the when. Attention is turning to this autumn, either before or shortly after the Labour Party conference in Manchester starting on September 20. The argument for then is that things cannot be allowed to get worse. But there are two caveats: some of the current pressures will blow out over August while some MPs, however despairing of Labour’s prospects, still believe that Mr Brown should be given more time, although that group is getting smaller; and some MPs fear that, if Mr Brown were to be replaced as Prime Minister this autumn, it would be very hard to resist calls for a general election next year when the economy is still doing badly and living standards are being squeezed. So some MPs favour a delay until after the local and European elections next summer. This is, of course, a way of avoiding a decision.

Thirdly, the who. There is no obvious or agreed successor. Jack Straw, the experienced caretaker, Alan Johnson, the union man with the populist touch, and David Miliband, the face of the new generation, all have their advocates, but there is no evidence that any would do better than Mr Brown in improving Labour’s fortunes. (All this is very different from autumn 2003 when the procedures for removing Iain Duncan Smith as Conservative leader were simple and there was an obvious successor in Michael Howard.)

That leads to the fourth question of whether. Would a new leader reduce Labour’s losses at the next election or would the - probably bitter - process of changing the leader twice in a Parliament make matters worse? Previous Labour Prime Ministers such as Clement Attlee in 1947 and Harold Wilson in 1968 faced talk of plots and revolts and looked vulnerable, but survived. Mr Brown will not be easy to shift.

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