Lots of people, it turns out, want Jeremy Corbyn to become Labour’s next leader. In addition to Unite and several other unions, the general secretary of the Communist party of Britain, more than 60 constituency Labour parties and – according to a poll on Tuesday – 43% of Labour party members, he has other, more unexpected supporters.

“Yay! Just yay!” tweeted Douglas Carswell, the Ukip MP when news of Corbyn’s polling result broke, while rightwing commentators urged Conservatives to register as Labour supporters to get him elected, under the banner #ToriesforCorbyn.

Owen Jones meets Ukip’s Douglas Carswell Guardian

What is less clear is whether Corbyn actually wants – or ever expected in his wildest dreams – to lead the Labour party. Explaining his decision to enter the race at the very last minute – he achieved the necessary nominations just two minutes before the deadline – the Islington North MP said he was responding to “an overwhelming call by Labour party members who want to see a broader range of candidates and a thorough debate about the future of the party”.

But could the man who wanted merely to shape a debate really find himself instead in charge of a defeated, bruised and poisonously divided Labour party? The bookmakers may have given him joke-candidate odds of 100-1 at the start of the race, but few in the party are now laughing, with senior Labour figures queueing up to prove it is not possible to be too rude about 66-year-old Corbyn.

Those who said their heart was with him should “get a transplant”, said Tony Blair on Wednesday. The MPs who had nominated him were “morons”, said Blair’s former adviser, John MacTernan. In this context, the Sun’s description of the MP as a “dangerous Marxist throwback” could almost be seen as a compliment.

Happily for Corbyn, a decades-long career on the Labour left breeds nothing if not a thick skin. He was born in 1949 in Chippenham, Wiltshire, the son of an engineer father and maths teacher mother, and attended a local grammar school where, a schoolfriend told the Sun, he stood in a mock election in the early 1960s as one of just two Labour supporters – “at a middle-class boarding grammar school in leafy Shropshire, there weren’t many socialists. We were trounced.”

Tony Blair urges those who say their heart is with Corbyn to ‘get a transplant’. Guardian

He joined the party at a young age and became active in student politics at North London Polytechnic (where he didn’t finish his course). Aged 25, he was elected a Labour councillor in Haringey, north London, while working for the National Union of Public Employees. He was elected to parliament in 1983, part of an intake that included both Tony Blair and Gordon Brown.

Labour’s politics may have shifted since those days, but Corbyn’s determinedly have not. He remains a self-described socialist and a long-time member of CND, of which he is vice chair, and is chair of the Stop the War coalition, which he helped to found in 2001.

A committed advocate of the anti-apartheid movement in the 1980s, he provoked a storm when, along with Ken Livingstone, he invited the Sinn Féin leader, Gerry Adams, to speak in London in 1984, at the height of the Northern Ireland Troubles. He has also attracted controversy over his links to organisations alleged to have connections to Hamas.

Even Corbyn’s interests conform pleasingly to type for a bearded vegetarian and Morning Star columnist: trains, his allotment, cycling. Though he is discreet about his private life, the MP chose to speak out in 1999 alongside his second wife, after he ended their marriage over her decision to send one of their three sons to a grammar school. He has since married Laura Alvarez, a Mexican who imports Fairtrade coffee.

As for the famous beard, Corbyn has called it “a form of dissent” against New Labour, and his beige jackets and black Lenin cap – which, the joke goes, date back as many decades as his political career – only add to the effect.

Corbyn has voted against the Labour whip more than 500 times since 1997, making him the most rebellious of all his party’s MPs – and now, favourite to be its leader.