Mr Mandelson is not going to resign over this new claim

'One of the most productive three-way relationships in politics has become one of the most destructive'

Perhaps Peter Mandelson's former house in Notting Hill is due for a blue plaque. It would say, I guess, that for a few years it was the most famous house in England; and that it became a leitmotif for what what went wrong for a government for which much went right. Suddenly, the loan which secured it has become a story again, with lender challenging borrower's account of how it happened. It's a story which matters a lot less for itself than for what it says about the government it has haunted.

Perhaps Peter Mandelson's former house in Notting Hill is due for a blue plaque. It would say, I guess, that for a few years it was the most famous house in England; and that it became a leitmotif for what what went wrong for a government for which much went right. Suddenly, the loan which secured it has become a story again, with lender challenging borrower's account of how it happened. It's a story which matters a lot less for itself than for what it says about the government it has haunted.

There are, it's true, real differences between the accounts of Geoffrey Robinson and Peter Mandelson. The first is the entirely new fact that Mandelson telephoned Robinson at 9am the day after their famous Grosvenor House dinner and asked "rather anxiously if I would really help him to buy a house".

The second is in the detail of the conversation the previous night. In the Mandelson version, it was Robinson who, after Mandelson's complaints about his "poky little flat in Clerkenwell", dwelt on the need for him, as a future Cabinet minister, to have a "good home" and a "proper base" to entertain and "be settled". In Robinson's version, it was Mandelson who uttered a cri de coeur by complaining that he did not even have a "decent flat where he could relax and entertain friends", adding that he would like to live in Notting Hill, and then concluding plaintively: "But it's too expensive and there is no-one to help me."

The question is whether, three or four years after the conversation took place, the two differing memories of it are quite as incompatible as yesterday's stories suggest. Because the conversation was, by its nature, private, we can't be sure, for example, that both men didn't say both things. And on the basic sequence of events, namely that Mandelson originally raised the issue of his quest for somewhere new to live, and that Robinson then suggested he might be in a position to help, both men seem agreed. Mr Robinson did after all say in his evidence to the Select Committee that "I offered to help if help was needed." And they also agree that the principal purpose of the dinner was to discuss the continuing difficulties between Mandelson and Gordon Brown.

Geoffrey Robinson, nonetheless, goes on to make clear why he feels that these details are important. He mentions the account in my book about Peter Mandelson, and then says "there is almost the implication that I put him up to [the loan]." He correctly assumes that the narrative of the home loan was largely, as my book makes clear, based on Mandelson's own version. Indeed, in most material respects it was very similar to the account that Mandelson subsequently gave to the Commons Select Committee on Standards and Privileges on 18 May, 1999.

Robinson then goes on to say that "intentionally or not, Peter has contributed to the image that certain sections of the Press have tried to create of my buying influence, power or even office." Understandably, Robinson goes on to say that he resents that implication. But was it made?

I can't speak for Mandelson - though in the one longish conversation I had with him about the loan when I was hastily revising my book after his spectacular resignation, he made no such suggestion. But I can speak for my book, which not only doesn't seek to imply that Robinson, a famously generous man, was seeking to buy influence but explicitly suggests that he wasn't. It points out that, from Robinson's point of view, the very point of keeping the loan secret was precisely to ensure that its existence could not be used to extend his influence. It strongly criticises, not Robinson but Mandelson over the loan - not least for failing to disclose it to the Prime Minister, the Cabinet Secretary, the Permanent Secretary at the DTI, or those journalists who began to ask him about the financing of his house during 1997 and 1998. So, far from suggesting, moreover, that Robinson lured him into the loan, it points out that Mandelson was not the victim of "some elaborate honeytrap", that it was agreed by him "of his own free will", and that the "responsibility for taking the loan was Mandelson's and his alone".

None of this is to say that the latest fuss over the Robinson book therefore doesn't matter. It does. This isn't just - or mainly - because Elizabeth Filkin, the Parliamentary Commissioner for Standards, might be tempted to reopen the home-loan case if she could. It was despite her own critical report, after all, that the Commons committee let Mandelson off with a reprimand in June 1999. It may not even be primarily because of Mr Robinson's damaging claim that he helped to finance Tony Blair's as well as Gordon Brown's office in the run-up to the election. It is really because of what it underlines about the personal feud at the heart of government.

It's hard to believe that Robinson, in suggesting that Mandelson is the destabilising element in what would otherwise be a harmonious relationship between Brown and Blair, does not faithfully echo the views of his close friend and former ally, the Chancellor. It is not a secret that the Chancellor finds it difficult to handle the fact that Blair listens to Mandelson's advice as well as Brown's. This is odd, given that Brown remains a significantly more powerful figure within the Cabinet than the Northern Ireland Secretary, and that Prime Ministers usually tend to take advice where they choose.

But the roots are actually buried deep in the leadership crisis after John Smith's death. Brown's resentment is well attested - not least at Mandelson's decision, finally, to back Blair. What had been one of the most constructive three-way relationships in 20th-century politics became - at times - one of the most destructive; a "love triangle" (in the words of one observer at the time) became fractured. But while the roots may be personal and emotional, the consequences threaten to be political, not least on the euro, the subject of Robinson's extract today, and on which Brown and Mandelson, and perhaps Brown and Blair, could still end up differing deeply after the election.

There are human factors in much of this story. Anti-Robinson briefings about the former Paymaster General being an embittered man hardly help. It would be pretty understandable, after all, if Robinson felt angry that Mandelson got back within 10 months of their twin resignations and he didn't. More poignantly still, it was a fairly self-destructive act of Mandelson's not to invite Robinson the housewarming party in 1997 at the home he had helped to finance.

That said, there is no sign that Mandelson, having had to resign once, will suddenly again be regarded by the Prime Minister as vulnerable because of this revival of the home-loan story. John Prescott is even said to have telephoned his backing from Peking for Mandelson, his long-standing colleague and frequent adversary. Instead, having survived so many vain attempts, largely by the Prime Minister, to end it, the enmity the story illustrates needs, finally to be controlled. If it can't be, it may yet contain the seeds of this government's eventual self-destruction.

* The writer's 'Mandelson and the Making of New Labour' is now in paperback (HarperCollins, £6.99)