John Rentoul: Whatever this is, it isn't serious politics

Gordon Brown's reshuffle measures up neither to the demands of the hour nor the challenge posed by the Conservative Party

Gordon Brown was hailed as the great strategist but Peter Mandelson's recall reveals the Prime Minister as simply tricksy. The Government is bereft of policy substance – outflanked for the second conference season running by George Osborne, who again identified an unpopular tax and announced a plan to which Alistair Darling will have to respond. So Brown resorted to personnel changes as a way of delivering a shock to expectations. I suspect that it will end in tears, but not for the reasons that dominated the early reaction of journalists unable quite to believe their luck in having the Prince's tail to tweak again.

Peter Mandelson is far from the scheming and manipulative politician of popular caricature. I defer to no one in my respect for his ability as a minister. He was admired and even loved by civil servants: clever, direct, hard-working and fun to work for. As European Commissioner he has proved himself a tireless negotiator and a fine advocate of free and fair markets. The Doha trade liberalisation talks failed despite his efforts, not because of them.

No, the downsides of Mandelson's appointment do not arise out of who he is but of who Brown is. The Prime Minister thinks he has done something clever. Gordon Brown knows that Mandelson's reputation with the media and the general public is unflattering. He knows that he has offended the Daily Mail. He knows that most voters will regard Mandelson's return with bafflement tinged with hostility. But he thinks that this is a price worth paying for the advantages. Of course, those advantages include Mandelson's experience as a player on the global economic stage. But Brown also thinks that he is buying off the Blairites in the Government.

That is where he may have "calculated too much", to quote Tony Blair's defence of a more instinctive approach. Brown intends his embrace of his great enemy to apply electric shock treatment to the deep psychology of the factional rivalry that has divided the top of the Labour Party for 14 years. As with his equally gimmicky cup of tea with Margaret Thatcher, he wants to convince the Blairites that he really has changed and become a bigger, inclusive, forgiving personality.

No chance. Peter Mandelson is a more potent hate-figure for the Brownies than he is an idol for the Blairites. Ed Balls, the Education Secretary whose eyes are firmly fixed on the Labour leadership contest after the next general election, is said to have opposed Mandelson's return. In other words, he has got his retaliation with a bargepole in first, so that if it all goes wrong he can say that it was nothing to do with him.

The Brownies feel betrayed, but the Blairites are not taken in. They are not even assuaged by the shooting of the messenger, Damian McBride, the Prime Minister's press secretary whom they suspect of briefing against them. Partly this is because he has not actually been taken out and shot, but merely invalided upstairs to a back office where he will have time on his hands. The Blairites see Nick Brown, restored to Chief Whip, as a manifest of the Prime Minister's true intent. They see him as a factional operator whose loyalty is to Gordon rather than the party.

That is where the faultline will open up. Mandelson, like Alastair Campbell and Philip Gould, both of whom publicly lent their shoulders to Gordon's wheel in Manchester, is a tribal Labour loyalist. What tribal Labour loyalists do in public is support the leader. But if they decide in private that it would be in the best interests of the party to replace the leader with, say, David Miliband, then they will see it as their duty to further that objective. At the moment, they are shouting from the kitchens, "Miliband's off". Politics is a cruel business. One bad speech and a banana and your career seems over. But it's an unpredictable business too. A foreign crisis and some intensive facial-expression coaching, and the Foreign Secretary could be back in the frame; or someone else might emerge.

The question is whether this reshuffle strengthens Brown for when he faces a renewed challenge. For the moment, the financial crisis has saved him. The Prime Minister is now in the crazy situation of hoping for more economic bad news, because the opinion polls suggest that the voters regard the man who got us into this mess as the best to get us out again. David Cameron is in the even crazier situation of hoping for a few more bankrupt banks, because if Brown survives until the election the Tories think they will win.

Hence the economic war cabinet that Brown announced last week. Although a twice-weekly meeting of 18 people sounds like Seventies statism gone mad, with any luck nothing will be decided and little damage will be done. Brown said that the new council consisted of "serious people doing serious jobs in serious times". I couldn't take him seriously. He reminded me of the large man in dark glasses on the children's TV show Robot Wars saying of his machine, Plunderbird: "It's a serious bit of business. We're going to do some serious damage with it. Because we're serious people."

The thing about being serious is that you do not need to say you are. With this reshuffle, Brown has proved that he is not. He has proved that he is more interested in factional calculation and presentational effect than in substance.

Last week the Conservatives caught him out with the plan for a two-year freeze on council tax. It wasn't difficult to work out how unpopular council tax is and how unfair it is seen to be. Alex Salmond, First Minister of Scotland, worked it out and promised a month ago to abolish it. But instead of panicking and working out how to head off the electoral threat, Labour mocked Salmond and wandered daydreaming into the Tory trap.

On top of that, the Conservatives pushed the idea of a new high-speed North-South rail link. If you are serious – without having to say so – about trying to reverse the rise in carbon emissions from domestic transport, this is a no-brainer. The idea was mentioned to me by a Labour person six months ago as an example of the kind of bold, simple and right initiative that Brown ought to be announcing.

Instead, we got an economic talking shop and a surprise reconciliation. That is not serious.