No week of misery for the Prime Minister would be truly complete without an intervention from Charles Clarke.

Although long anticipated - Mr Clarke promised over the summer that there would be something - the timing of the former Home Secretary’s remarks is still deeply unhelpful.

While many in the party wanted Mr Brown to be given a clear run to lay out his economic relaunch - the latest stage is a major speech to the Scottish CBI tonight - Mr Clarke appears to have ended this temporary truce early.

He used a New Statesman article to issue a rallying cry to other Labour MPs concerned at Mr Brown’s performance to come forward and speak out - rather than sit on their hands and lead the party to disaster at the next election.

On the BBC Radio 4 Today programme this morning he went further and gave the Prime Minister “months” to turn around the party’s fortunes or step down - either voluntary, or in the face of a Cabinet coup.

Mr Clarke is a well known opponent of Mr Brown - he previously labelled the Prime Minister ‘deluded’ and a ‘control freak’ - but his intervention will still hurt.

But the former Cabinet minister's prediction that Labour could be “utterly doomed” may turn out to be a self fulfilling prophecy by reinforcing the impression that the party is still distracted by infighting.

There are certainly many in the Labour party complaining privately about Mr Brown, but few beyond Graham Stringer and a handful of left-wingers have been prepared to speak publicly.

Allies of Mr Brown are putting on a brave face this morning, saying they were braced for worse than this - rumours have been circulating for months of a round robin letter calling on Mr Brown to go, or the co-ordinated resignations of members of the government.

And, in many ways, Charles Clarke’s intervention this morning is interesting for what it did not say.

He did not call on Gordon Brown to go immediately. Indeed, by saying he had “months”, he appeared to have given the Prime Minister longer than his own Chancellor, who told The Guardian he had “ up to party conference”.

He also said there was no appetite in the Cabinet to force him out at the moment.

So if nobody comes forward to answer Mr Clarke's cry, will he end the day looking isolated?

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