Former critics lined up to praise Jeremy Corbyn after Labour secured its biggest increase in the share of the vote since the War - but the knives are still out for the veteran socialist among some of his own MPs.

Last night a fierce former opponent of Mr Corbyn became the first to announce that he could re-enter the shadow cabinet.

But another party source said that Islington North MP “could still be out by Christmas”.

Former Business Secretary Chuka Umunna, said that the Labour leader deserved credit for the party’s campaign.

He said he would take a job "if I'm asked, but I make absolutely no presumptions".

But behind the scenes others continued to criticise the Labour leader, pointing out that he won only a handful of seats more than Gordon Brown in 2010.

Other Labour MPs are expected to follow Mr Umunna's lead in coming days.

Mr Corbyn has two immediate spots in his frontbench team to fill, that of the shadow Scotland and shadow Northern Ireland secretaries.

In a sign of how depleted Mr Corbyn's previous team was, both vacancies have been created by the retirement of just one MP, North East politician Dave Anderson.

Mr Corbyn no longer has to rely on his sole MP north of the border, Ian Murray, now that he has a handful of Scottish Labour MPs.

The shadow Northern Ireland role could also be critical after Mrs May announced plans to government with the Democratic Unionist Party.

Elections experts Professor Michael Thrasher said that high turnout at the election suggested that Labour's success was being fuelled by an increase in younger people voting.

Mr Corbyn started the election campaign more than 20 points behind Theresa May's Conservatives in the opinion polls.

But the Labour leader benefitted from Mrs May's forced U-turn on controversial plans to pay for social care in England.

His own manifesto proved popular, with proposals to re-nationalise railways, and to provide more free childcare and free university tuition fees south of the border.

Criticised by the Conservatives for believing in a "money tree", Labour appear to have appealed to voters sick of seven years of austerity.

The party saw astonishing returns in some constituencies.

In Ealing Central and Acton, a seat the party had been widely expected to lose at the start of the election campaign, Labour's Rupa Huq increased her majority from just 274 to almost 14,000.

Mr Umunna said that the party still needed to understand why it had failed to convert Tory voters to its message, suggesting that only a broader base could allow it to retake the keys to Downing Street.

But as the results poured in some of his strongest critics heaped praise on Mr Corbyn.

Owen Smith, who challenged Mr Corby for the leadership last year, said: “I think Jeremy has cut through with the reality that Labour offers a very different set of priorities and choices to the public in a way the previous Labour shadow administration didn't.”

Hilary Benn, sacked by Mr Corbyn amid claims he was encouraging a coup against the leader, told the Financial Times: "A lot of young people have been enthused by Jeremy's campaign."

However, he added: "We have not won. It is the third election in a row that we have not been able to form a government. The party will want to reflect on that."

The party finished with 262 seats, up 30 on 2015, while the Tories lost their overall majority after seeing their tally of MPs fall to 318.

Even former Business Secretary Lord Mandelson said that he had been “wrong” about Mr Corbyn. admitting that he had been “working every day” to bring him down earlier this year.

"I was wrong," he said. "I am very surprised, an earthquake has happened in British politics and I did not foresee it."

But he added that he remained unconvinced that Mr Corbyn could secure a Labour victory at a future general election.

Lord Blunkett, another former party 'big beast', praised the Labour leader’s “superb job” in mobilising voters, having previously predicted that the party would be “annihilated” at the general election.

“All credit to Jeremy Corbyn. The anti-austerity campaign that he led has been extremely effective, backed up – it has to be said – by those who didn’t always agree with him,” he said.

“I just want to say this to Jeremy: you’ve done a really superb job at mobilising, including young people. Could we mobilise in parliament behind you by you being a statesman, not just a campaigning leader but someone who’s prepared to say ‘yes, I will heal the rift, I will reach out, I will have an elected Shadow Cabinet’?”