“I WAS hugely disappointed to see the Labour Party vote in favour of further austerity and in doing so we have done hardworking people a great disservice,” said Diane Abbott in January.

“Instead of simply mimicking current practices we should be offering a solid alternative.”

So said the Labour MP after all but four of her colleagues voted in favour of George Osborne’s charter for budget responsibility and its timetable to eliminate the deficit through cuts.

Neither Jeremy Corbyn or John McDonnell voted on the issue, but we know how they would tomorrow, despite the misgivings of their shadow cabinet ally.

In an extraordinary volte face yesterday, Mr McDonnell, now the Shadow Chancellor, said he expected Labour MPs to support Osborne’s charter for a budget surplus by 2019-20.

“We are not deficit deniers,” he said.

The change of heart, on the eve of Labour’s first conference under Corbyn, is understandable - voter distrust on economic competence was key to Labour losing the election - but it is not a credible shift, and it only underlines the almighty mess in which the party now stands.

Corbyn became leader by preaching an unremitting anti-austerity message, and he was rewarded with an overwhelming mandate for change.

What, then, are his supporters to make of him embracing a Tory tar-baby like this?

Osborne, already elated at Corbyn’s win, must now be entering a state of bliss.

True, McDonnell stressed Labour wanted to balance the books and tackle the deficit in different ways to the Tories, and that would be a dividing line between the parties.

But that will be an impossible sell over the coming parliament, because Labour will not be in a position to do put anything different into practice.

Instead, its MPs will have to listen impotently to the swish of Osborne’s axe and the Chancellor reminding them they signed up to the broad strokes of his deficit reduction plan.

Given Corbyn’s own record of rebellion, it is hard to imagine Labour MPs suffering that long on his account, and a mutiny must be on the cards.

A splits is also certain on the conference vote on whether to back the renewal of Trident.

Corbyn has long opposed the nuclear deterrent, and so do many of his supporters.

But many of his MPs sincerely believe it should be retained, as do trade unions with members in the defence industry - the GMB said last week it would be “madness” to scrap Trident.

Of course, these policy debates may yet refresh Labour’s sense of purpose - in time. But with Scottish, London mayoral and English council elections in May, Labour does not have time.

In all likelihood, it will go to the country divided and unelectable, and the countdown clock on Corbyn’s tenure will begin.

It is hard to see a way out. McDonnell’s position on the fiscal charter certainly doesn’t help, but whichever way Labour turns, it appears to face disbelief, division and failure.

For the Tories, who meet next month in Manchester, this Labour conference could hardly be a more enjoyable curtainraiser to their own.