This comes at the end of the worst period of Mr Blair's leadership to date. From Harriet Harman's schooling problems through shadow cabinet bickering to Michael Meacher's "old Labour" line on welfare, it has been a cool spring for the Labour leader. Many of the reasons for this faltering in Mr Blair's steady stroll to Number 10 can be found by unravelling Lord Jenkins's notion of him as a new Gaitskell.
The Blairites have hardly wrapped themselves in Gaitskell's memory; his name is absent, for example, from Peter Mandelson and Roger Liddle's book, The Blair Revolution. This at first seems curious. After all, Gaitskell was the original moderniser; he was at the cutting edge of political discourse in the 1950s; he tried to ditch Clause Four; and when he took on the old loyalties of his party he even employed the services of a spin doctor - the market researcher Mark Abrams. But if Mr Blair is silent on this past it is no accident, for to compare the two leaders is to associate Mr Blair with a politics of ethical collectivism whose objective was greater equality - an idea with no place in New Labour.
Today Gaitskell looks like a political dinosaur. He did not believe in the market, but in planning. He believed Labour should govern because it understood better than the Conservatives the "modern" interventionist economics which would solve the problem of distribution. Politics in his time were within terms of reference set by Labour: collectivism was on the march.
Mr Blair does not operate in an intellectual environment shaped by his party, nor does he believe he has an economic theory that provides an answer. Instead he is playing catch-up to a revolution instigated from the right. Collectivism is dead; the market rules. Because of this it is unclear quite what a Blair government will be for. There would have been no such ambiguity about a Gaitskell government - had he lived to form one.
Gaitskell's beliefs, moreover, were set so deep in him that he would not have been able to shed layers of ideological commitment with the ease which characterises New Labour. There were intellectual and emotional limits to Gaitskell's revisionism that might have tripped him up as premier. I am not aware of there being similar limits for Mr Blair.
Yes, Gaitskell would have moved to the right of his manifesto's economic policy if he had been elected, as indeed every Labour government since the war has done. But Tony Blair in opposition has already moved a long way to the right; if he wins power the question must be: how much further will he go?
Some Labour backbenchers hope that despite the anticipated fiscal conservatism of a Blair government, MPs will be able to devote their radical energy to constitutional and other reforms. This hope further highlights the problem with Lord Jenkins's Blair-Gaitskell comparison. Outside the economic field, Gaitskell held solidly libertarian beliefs: his Labour Party, for example, opposed all immigration controls, he wanted to liberalise the divorce laws and he supported homosexual law reform.
The ethical basis of his socialism was secular; he was no puritan, though he worried about the increasing materialism of society; his socialism owed more to logical positivist ideas than to Christian metaphysics. In sum, Gaitskell was more radical in the social arena of politics than in any other, whereas the Labour Party of Tony Blair is at once economically liberal and socially conservative. Not since Gladstone have we seen political leaders so influenced by Christianity. We have already seen Labour allowing a free vote on divorce (rather than adopting a policy on change) and a recasting of Labour's family policy which effectively puts the "nuclear" back in. The full impact of these influences on a Blair government remains to be seen.
The touchstone for Gaitskell was rationalism. On Europe, when Jean Monnet, the architect of the Common Market, told him European integration was a process in which he should have faith, he replied that he did not believe in faith; he believed in reason. He was a patriot and a nationalist who believed Britain had a global role to play and that democratic socialism offered a real hope of a better society. Such core beliefs would have given a Gaitskell government a clear underlying identity. His Cabinet would have squabbled, but deep down they would have understood why they were in office.
By contrast, everything points to a schizophrenia at the heart of the modern Labour Party. One part is desperate for power. It has abandoned all pretension to setting the agenda and offers little more than a gentler and more Christian version of post-Thatcher consensus politics - except, perhaps, in the area of constitutional reform. The other part remembers, meanwhile, that promoting greater equality is what Labour was made for and worries that there is no clear purpose behind electing a Blair government.
For all these reasons Tony Blair is no Hugh Gaitskell, and the implications of this run deep. No one knows what Mr Blair is for and no one knows what a Labour government will be for. The autumn party conference may be the opportunity to clear some of this up, perhaps by breaking the link with the unions or by changing the name of the party. If they choose the latter course, there is one name that would fully express the nature and extent of the party's metamorphosis: they could call themselves Christian Democrats.
Brian Brivati's biography of Hugh Gaitskell will be published by Richard Cohen Books in September.