His time as leader saw him outlast two Tory prime ministers and transform Labour's identity from a party of pragmatism to one in favour of radical change as he rode a wave of anti-austerity resentment.

But no one was perhaps more surprised than Corbyn when the serial rebel and stalwart of the party's left was thrust into the top job.

The anti-war campaigner, who has represented Islington North since 1983, had to be persuaded to run as an outsider candidate for Labour's leadership after a crushing general election defeat in 2015 left the party in need of re-invigoration.

He scraped onto the ballot paper thanks to the nominations of non-supporters

hoping to broaden the debate.

Those colleagues had not expected the meteoric rise that followed when the party's membership, swollen by supporters joining under new rules, overwhelmingly voted for him in September of that year.

The move was much to the indignation of many in his parliamentary party, and he suffered a shadow cabinet walkout and a no-confidence vote with fears he was electorally incompetent.

But he survived the effort to dethrone him with a second leadership election,

thanks to his overwhelming popularity among grassroots members.

Having already seen the demise of David Cameron with his loss of the EU referendum, Corbyn headed into the 2017 general election with the polls suggesting his prospects were poor.

He did not win, as some of his supporters may have you believe, but he did not

suffer the humiliating defeat many predicted.

Instead Labour won 40 per cent of the vote, vastly improving on Ed Miliband's share, and stripping Theresa May of her majority.

It is ironic, then, that May's effort to bury Labour instead gave Corbyn's credentials a major boost and bolstered his image as a credible leader.

That election saw him win the hearts and minds of many younger voters, encouraging in them a taste for drastic change.

Just two years later, and in the face of heavy losses for Labour, the inquest is already beginning into what went wrong.

The veteran campaigner was seen as having only tepid enthusiasm for his work in support of remaining in the EU.

And Labour's Brexit stance was widely seen as ambiguous, particularly in the face of the unequivocally Remain-backing Lib Dems.

Another major concern for many potential voters was his perceived failure to

eradicate the scourge of anti-Semitism in the Labour ranks.

After saying he would not lead his party in any future election campaign, Labour's once-reluctant leader will soon have more time on his hands to spend on his beloved allotment.

Australian Associated Press