Why on earth does Tony Blair want Ken Livingstone back in his party?

If nothing else, Tuesday's decision by the National Executive removes any doubt, if doubt there still was, that Ken Livingstone remains a world class political operator. By opening the way to the readmission of Ken to the Labour Party, the NEC has played, right on cue, its part in the flightpath determined by the London Mayor from the moment it voted to keep him out of the party in the summer of 2002.

None of the reasons that applied then, have changed, of course. His formal five-year suspension from the party for breaking his cast-iron promise not to stand as an Independent against the Labour Party candidate still has two years to run. What has changed is Tony Blair's flexible and ultra-pragmatic mind in the face of what he now sees as the imperative of avoiding a spate of bad headlines caused by the wipe-out of a weak Labour candidate in the London elections on 10 June next year.

A candidate who was conveniently chosen - of course - by Livingstone himself. It was Livingstone, as he told my colleague Paul Waugh with commendable frankness in an interview last year, who first proposed to Nicky Gavron that she stand as the Labour candidate. It was Livingstone by whom the party's membership were mesmerised when they opted for Ms Gavron. It was Livingstone for whom Ms Gavron said she would urge her supporters to cast their second preferences in next year's election. And it is Livingstone who is the one incontrovertible beneficiary of Ms Gavron's announcement - also right on cue - that she is now standing down as the candidate. Don't you love it when a plan comes together?

Ken Livingstone has not been a bad mayor. His achievements are limited. But by reducing bus fares, he pushed up the bus use when it was falling everywhere else. He has raised police numbers. He has said some sensible things about the need for investment in London. And even if he wilfully prolonged the agony over the Tube by taking the Government to court, congestion charges have been a real success.

But this isn't about whether Ken should have a second term as mayor. It's not as mayor that Livingstone has been the disaster that Blair predicted he would be when he bravely toured London party meetings to fight against Ken's attempt to be the Labour candidate in the run up to the 2000 election. His disastrousness has been as a leading personality in the Labour Party And the present crisis is precisely about whether he should set an extraordinary precedent by being allowed, well before his suspension has run out, to rejoin the party whose electoral fortunes he spent a large part of the 1980s and the early 1990s undermining.

It's wholly understandable that Neil Kinnock, the man who did the heaviest tramping of all in the roughest, earliest stages of Labour's long march back to electability should be incandescent at the idea of his readmission. And that John Reid and Charles Clarke, who were Kinnock's close lieutenants on that march, should also be opposed. And that John Prescott, personally affronted by Livingstone's broken promise, should be even more fiercely against it. Or that Gordon Brown, for whose sacking Livingstone was already fatuously calling within a mere 13 months of the Labour government taking office, is of like mind. Or that Hilary Armstrong, as Chief Whip responsible above all others for party discipline, should shudder at the prospect. What is utterly baffling is why Blair should now take a contrary view to that of this uniquely experienced group of his Cabinet colleagues.

From the cosy and prosperous metropolitan enclaves of the party so well represented by Ms Gavron, a seductive counter-argument wafts outwards. The Labour Party is nothing if not a broad church. The '80s were the '80s. Never mind that Livingstone infuriated even his own colleagues on the hard left of the party as late as 1994 by trying to run as party leader. It's time to move on.

Well, can anyone be confident that Livingstone, who denounced the Prime Minister's guest George W Bush as "the greatest threat to life on this planet", will not resume his charismatic and destructive role in the party? Or that every dispute he has on - say the huge funding gap for Transport for London - will not be turned into a political crisis within the party? Or that he will not be elected to the National Executive as the darling of the unions who are now backing his readmission? Or that he does not still harbour ambitions to lead the party? Or that so far from being constrained in his behaviour by being inside the party, he is actually constrained by being outside it?

From the deep interstices of the Blair circle, however, emerges a more hard-headed but, in the end, equally unconvincing explanation of the shabby fix now in the making. Gavron was a disaster, not only in danger of coming fourth - or even fifth - but might anyway have pulled out at some future point before the election. A majority of London Labour MPs have persuaded themselves that he should return to the fold. If Blair had advised the National Executive not to begin the process of readmission, he might have been defeated on Tuesday.

So what? one is tempted to ask. Would that have mattered so much if Blair had fought for the principle that five years is five years and was backed in doing so by the most senior members of his Cabinet? What isn't clear, however, is how diligently Blair and his advisers have sought an alternative way out of their problem.

The Prime Minister has not, for example, personally summoned Tony Banks, the runner-up to Gavron in last year's candidate selection, to use his famous charm to persuade him to carry the Labour banner against his old adversary and fellow-left winger Ken. No doubt the informal and highly hypothetical soundings of Banks by a third party established he was pretty fed up, as he well might be after being persuaded to run last year by the party hierarchs only to fall victim to the Livinsgtone spell. All a laconic Banks would say yesterday was that the "proposed deal [to bring Livingstone back as Labour candidate] is stripping the dignity out of the Labour Party." But I can't help thinking that Banks, a party loyalist above all else, would find it very difficult indeed to turn down a direct and personal appeal from the Prime Minister to step into the breach.

But maybe Blair doesn't want that. Maybe he is now determined to offset the dangers posed to him by bad local and European election results next June by cashing in on what the polls certainly suggest will be a Livingstone victory. Even tactically, this may be a mistake. It's likely that the public at large will see this for what it is - a Wilsonian fix.

But as a matter of principle, almost anything, even not having a Labour candidate at all, is better than what is now envisaged. There isn't much time now to block Livingstone and find an honourable way out. But Blair's USP was changing the party once and for all. If even that is sacrificed to short-term electoral expediency, you have to wonder, at least in party terms, what's left?

d.macintyre@independent.co.uk