It is a stubborn fact of the past 80 years of Labour history that only three people have had the privilege of winning a general election in the party’s name. Two of those people are long deceased. The third still breathes, but much of his party has recently behaved as if they wish their only living winner were dead.

Clement Attlee, Harold Wilson and Tony Blair were very different characters operating in very different contexts. Which makes it the more significant that the select trio all won for Labour in much the same way and for similar reasons. Each went to the country with a transformational programme. Rather importantly, they also understood that there was no point having such a programme unless you mobilised enough support to win the power to implement your plans.

This was not easy, for each of those winners had to combat ferocious attacks from the right. It is one of the self-mythologising convictions of Jeremy Corbyn that he faces a uniquely hostile environment. The truth is that there would never have been any Labour prime ministers if the Tories and their newspapers were the only arbiters of who should be in government. To try to stop Attlee, the Tories made the disgusting allegation that the Labour leader would introduce a British version of the Gestapo. Against Blair, Tory campaigners manufactured “demon eyes” posters, depicting him as the spawn of Satan.

According to Mr Corbyn, the powerful should be frightened because they will face “a reckoning” when he gets to power

Each of Labour’s winners prevailed because they had established sufficient credibility with the country to make Tory attacks seem wild and silly. They put their credibility into the service of a narrative of national renewal that resonated with a critical mass of the electorate. Attlee’s compelling pitch – “now let’s win the peace” – was about building a Britain worthy of the collective sacrifices made in wartime. Wilson, updating what it meant to be on the left of the spectrum for his era, planned to forge a “new Britain” in the “white heat” of “technological revolution”. This was not well realised by his governments, but it was a great help in broadening Labour’s appeal. For Blair, it was about allying economic competence with social justice to make a modernised Britain fit for the challenges of the 21st century. That blend was so effective, both as a formula for winning elections and as a method of governing, that he is the only person ever to have won three back-to-back terms for Labour.

Labour is tortured by its past and, perversely, that problem is most acute with the winning chapters of it. By contrast, the Conservatives are good at defending their history and, when convenient, they are also shameless about rewriting it. Without a blush, Mrs May’s manifesto will steal popular Labour policies that Tories had only recently denounced as Marxist. The right burnishes the memories of its past heroes. See how they still worship Margaret Thatcher, her many warts and all. When the left pays attention to its past, it is too often to despise it. Blair, as any passing Corbynista will let you know, presided over 10 years of reactionary policies such as making dramatic reductions in pensioner and child poverty, doubling spending on schools, raising the proportion of national income devoted to health to an all-time high and extracting record levels of taxation from the wealthy in order to redistribute the revenues to the less well-off. Wilson, in so much as he is remembered at all these days, was a slippery letdown. Only Attlee is accorded some reverence, though the prime minister who ensured that Britain had a nuclear deterrent would have had no patience at all for a party that wilfully did things that would deny itself power. This refusal to pay any respect to its own history is a large part of the explanation for why Labour’s future now looks so bleak.

Jeremy Corbyn’s manifesto will be formally published this week, having been pre-launched via a leak in the past few days. Though it will never be implemented, it is still worth paying attention to the Corbyn prospectus as an illustration of why Labour is in such a predicament. From nearly all quarters, friendly and hostile, a descriptive word of choice is “radical”. The Tories and their newspapers use the label pejoratively, likening it to the “longest suicide note in history”, as the late Sir Gerald Kaufman dubbed the 1983 manifesto that accompanied Labour’s severest postwar defeat. That attack from the right is embraced by Mr Corbyn and his devotees because it fits with their self-conceit that they threaten a “scared” establishment. According to the Labour leader, the rich and the powerful should be frightened because they will face “a reckoning” when he gets to power. The City is so petrified of Mr Corbyn’s plans to take rail franchises back into public ownership that the share prices of the operators were blissfully unperturbed by the leak of the manifesto. Investors in the Royal Mail, another candidate for renationalisation under a Corbyn government, saw the value of their holdings tick up a bit. As for the Labour leadership’s internal enemies, they don’t publicly quarrel with the notion that Corbynism is “radical”. They have been largely content to let him have his own way with the manifesto in the belief that this will allow them to assign ownership of Labour’s defeat to the left.

1983 v 2017: how Labour's manifestos compare Read more

The Corbyn prospectus is certainly left wing, but it is nowhere near as left wing as the ’83 manifesto. The Communist party of Great Britain and the other hard left groupuscules that have rallied behind Mr Corbyn may feel let down by the absence of a commitment to replace capitalism with a dictatorship of the proletariat. The better comparator is with the manifesto that Labour fought and lost on two years ago. In the wake of that defeat, the Labour left argued that the fault in Ed Miliband was not that he couldn’t convince enough people to trust him with power, but that he had been too timid. The left won that argument and used it to seize the leadership. The Corbyn prospectus is not so much Foot revisited as Miliband microwaved. Where he proposed to trim student tuition fees, Corbyn Labour would abolish them. Where Miliband Labour proposed to increase taxes on those earning £150,000 or more, Corbyn Labour would up the rates on those earning £80,000 and above. Think of a Miliband spending promise in 2015 and multiply it.

Some of the individual items are attractive enough to be stolen by the Tories at some point in the future. Many of the policies will poll well, as they did when their first iterations were presented to the public a couple of years ago. The same voters then rejected the package as a whole because it added up to less than the sum of its parts when it came to plausibility. For anyone who thought the only problem with Ed Miliband was that he wasn’t left wing enough, this is a generally enticing offer from Labour. For the larger number of voters who had different issues with Labour in 2015, there is nothing to persuade them that the party has absorbed their concerns and a lot to raise the suspicion that it hasn’t been listening at all. Real radicals draw up programmes with a view to implementing them; phoney radicals make promises they know they will never have to keep because the pledges are merely designed to shore up the core vote.

The word “radical” implies some fresh and bold thinking, not replating a double helping of the dish that two-thirds of the electorate declared unappetising just two years ago. It will be popular to spend more money on the NHS because it always is. But that is not a radical idea to find in a Labour manifesto. Certainly not as radical as setting up the NHS in the first place, one of the enduring legacies of the Attlee government. Seven decades on from its creation, injecting more funds into the health service may be the right thing to do, but it is also the easiest thing to propose, as I suspect most of the public intuit. A contemporary radicalism would be thinking hard about how the NHS needs to adapt to cope with the evolving challenges of the 21st century.

It will please Labour people to be promised an increase in the minimum wage to £10 an hour, but the truly radical breakthrough was establishing a minimum wage in the first place, one of the historic progressive achievements of Blair and his appallingly neoliberal government. Contemporary radicalism would involve some thinking about how to prepare for a world in which automation is already consuming jobs and could devour millions more. The Corbyn prospectus makes a gloriously retro proposal to resurrect the Ministry of Labour, which was judged unfit for modern purpose by Wilson all the way back in 1968. Whatever that is, it isn’t a component of a compelling narrative of national renewal.

I don’t think that I am giving away a secret when I say that Labour’s trio of winners will not grow into a quartet on 8 June. There are many reasons why the party is heading for another defeat and very likely an awful one. Being too radical is not really one of those reasons. The truly scary thing about Labour is that it is not thinking radically at all.