Peter Mandelson is to politics what the naked short seller is to corporate finance. Bringing back the @prince of darkness@ was one of those ideas that probably sounded great late at night after a few beers, but should have been abandoned in the cold light of day. What is worrying is that there is clearly no one around the Prime Minister capable of telling him so.

Yes ,I know all the arguments for having the former Labour spin-doctor back in cabinet - about ?keeping your friends close and your enemies closer?. Having Peter Mandelson in the tent stops the Blairites setting fire to it; grabs the attention of the business community; shows Brown is capable of commanding the news agenda; marginalises rivals like David Miliband; creates a kind of ?war cabinet? of all the talents to deal with the economic crisis. But really, this is not an act of decisive leadership; it is a gesture of Prime Ministerial attention-seeking . Brown couldn?t think of anything sensible to do, so he did something daft.

Why is it daft? Well first of all, because Peter Mandelson is, as the Labour MP John McDonnell poijnted out, the most divisive figure in Labour politics. He is an accident waiting to happen. He has resigned from cabinet twice ? the first time as Trade and Industry Secretary in 1998 after he failed to disclose a large loan he had accepted from a wealthy ministerial colleague, Geoffrey Robinson, who was under investigation by his own department. His second resignation, in 2001, followed his apparent canvassing for a passport on behalf of a billionaire businessman, Scrichand Hinduja. With form like this, every action of the new Business Secretary, will be under scrutiny by a sceptical press. Every disaffected official and political contact will be on the lookout for dirt.

.And is twice-disgraced Peter Mandelson really the man to clean up the City.? There is a lot of prima facia evidence emerging from the mortgage bust of fraud, malfeasance, misselling, accountancy irregularities and plain theft. Look at what we are learning about the corporate culture of banks like HBOS. Of Bradford and Bingley. How can Mandelson,with his record, be expected to crack down on bad behaviour by the banks? Yes, he has done the crime and served his time in political obscurity. But his resignations have fatally undermined his probity, and that will make it very difficult for Peter Mandelson to carry credibility when it counts, when dealing with the spivs and speculators. They will sense his moral vulnerability and will exploit it.

Moreover, Peter Mandelson is an evangelist for globalisation and deregulation right at the moment when free market idolatry has become discredited. He is the minister who famously said he was ?seriously relaxed about people becoming filthy rich?. Well, he should not be relaxed. It was the pursuit of extravagant personal gain that led to the breakdown in the financial system, as bonus-driven executives took greater and greater risks in their determination to become filthy rich before the system collapsed. At this crucial time we do not need someone in charge of the store who adores wealth the way Peter Mandelson evidently does.

As European trade commissioner, Peter Mandelson antagonised developing countries because of his commitment to free market globalisation and his willingness to expose vulnerable economies to the predations of supercapitalism. And it isn?t just development organisations like the World Development Movement who think he is a neoliberal bully. Mandelson managed to fall out spectacularly with the Chinese over clothing exports ? the infamous @bra wars~- and with the French President Nicholas Sarkozy over agriculture tariffs. The Doha round of international trade liberalisation collapsed under Peter Mandelson?s watch, and while he cannot be held entirely to blame for that, his unthinking commitment to globalisation certainly played a part in its downfall. The Prime Minister has hailed his experience in international economic affairs ? but what exactly does this experience bring to the UK cabinet as Secretary for Business, Enterprise and Regulatory Reform? Further deregulation, no doubt, of the kind that has turned Britain into an unstable hedge fund.

So, Peter Mandelson is unreliable, tainted with sleaze, handicapped in office, confrontational in negotiations and passionately committed to precisely the kind of unregulated financial globalisation that has brought the world economy to the bring of total collapse. But there is something much worse that Peter Mandelson brings to the cabinet table. He is the author of Labour?s original sin: spin.

I well remember, on the day of John Smith?s death in 1994, watching Peter Mandelson oiling around the Lobby in Westminster - where I was a political hack - working the press, easing Brown out and easing Blair in. Mandelson functions by cultivating a handful of press insiders who are fed stories provided they remain on message. Sometimes the stories are even true. He is an incorrigible manipulator of the media, a politician who simply cannot stop plotting and briefing. He tried on many occasions to give up his addiction to the black arts of spin after he entered government in 1997, and invariably failed.

A cabinet with Mandelson sitting in it will be a cabinet which is always looking over its shoulder, permanently waiting for the knife in the back. Brown hopes that they will all think Mandelson?s knife is now being wielded in the interest of the Prime Minister, and that this will keep them all in line. Like Stalin who used the psychopathic secret policeman Beria to frighten his politburo. But fear is not a climate that encourages stable and effective government.

Gordon Brown clearly feels rejuvenated, intoxicated even by his conference success and his recovery in the opinion polls. He feels he is in charge again, driving events, making headlines, just like the old days. But this isn?t the old days. Labour is a tired and discredited administration led by a Prime Minister who has lost his way and is profoundly unpopular ? more unpopular than any Labour Prime Minister in history. His attempts to surround himself with cronies and manipulators will not help him recover his political standing and will only diminish him in the eyes of history.

Gordon Brown faces his nemesis in Glenrothes in about four week?s time. Does he seriously think that Peter Mandelson is going to help him win that important by-election? Of course not. He expects Mandy to do what Mandy does, and find ways of creating diversions, identifying scapegoats, burying bad news. It is another profound shock to those who have always respected Gordon Brown as one of the great Labour politicians of his generation. That Gordon should have descended to this desperate rehabilitation of a discredited political fixer is not just bad, it is sad.