I was wrong about Jeremy Corbyn. I had already been wrong about him twice. I thought he would come fourth in the Labour leadership election in 2015, and I thought that, when he was exposed to the British public in an election campaign, Labour’s support would go down.

But I do try to learn from my mistakes, and so, knowing that I had been wrong about him, I tried to offset my own bias. I didn’t do a good job. I looked at all those polls and forecasting models pointing towards a Conservative majority of 100 or more, and I thought it would be less than that. I said the majority would be 78. Hopeless.

So now I will have to try harder to learn from my latest mistake. I put too much weight on assumptions for which there was little evidence. My colleague Jon Stone listed some of them this morning. One was that opinion polls tend to overstate Labour support. They have in the past, but most pollsters adjusted their methods after the last election. They seem to have overdone the correction. There was no way of knowing that, but I shouldn’t have assumed that, if there were an error, it would be to overstate Labour.

Jon also lists “Voters will never vote for left-wing policies”. I thought I was aware of the problems with that kind of simplistic assumption. I was well aware that some supposedly left-wing policies are popular, but I was confused, torn between pointing out that there is nothing left wing about public ownership and imagining that people would balk at adding to the national debt to pay for it.

General Election 2017: 6AM results - hung parliament confirmed

None of that matters. People think their gas and electricity bills are too expensive, and that the Government ought to do something about it. And they are sentimental about privatisation of rail and mail. People are also more worried about student debt than the question of who will pay for such a huge subsidy to better-off graduates.

I thought, too, that John McDonnell wanting an insurrection to bring down capitalism would go down badly with the median voter. It turned out that the median voter was pretty fed up with capitalism and didn’t mind a bit of anti-establishment rhetoric.

I also believed the polls when they said that Theresa May was preferred to Corbyn as prime minister, and that she had a particular advantage on Brexit, paying for economic promises and national security. But there were other things going on at the same time, above all a sense of compassion, enthusiasm and optimism, which compared badly with the emotional flatness of the Tory campaign.

General Election 2017: Big beasts who lost their seats Show all 7 1 /7 General Election 2017: Big beasts who lost their seats General Election 2017: Big beasts who lost their seats Nick Clegg Picture By Darren O'Brien/Guzelian Picture Shows Former MP, Nick Clegg delivers a speech despite losing the Sheffield Hallam Seat. Labour candidate, Jared O'Mara (Front), defeats Nick Clegg to take the Sheffield Hallam seat. picture taken 08/06/2017 Darren O'Brien General Election 2017: Big beasts who lost their seats Gavin Barwell LONDON, ENGLAND - OCTOBER 07: Gavin Barwell MP arrives at Number 10 Downing Street on October 7, 2013 in London, England. British Prime Minister David Cameron announced a Government reshuffle today. (Photo by Oli Scarff/Getty Images) Getty General Election 2017: Big beasts who lost their seats Angus Robertson General Election 2017: Big beasts who lost their seats Nicola Blackwood PA General Election 2017: Big beasts who lost their seats Alex Salmond PA General Election 2017: Big beasts who lost their seats Rob Wilson Mandatory Credit: Photo by Geoffrey Swaine/REX (1096138i) Rob Wilson, Conservative MP for Reading Funeral of Murdered Student Asha Muneer at Rivermead Leisure Centre, Reading, Britain - 28 Jan 2010 Rex Features General Election 2017: Big beasts who lost their seats Ben Gummer Minister for the Cabinet Office Ben Gummer arriving at 10 Downing Street, London for the weekly cabinet meeting. PA

I wasn’t relying just on opinion polls, of course. Labour did very badly in the local elections on 4 May. Those were real votes in real ballot boxes. I even met real voters. I came across Labour voters who liked Theresa May and others who didn’t like Corbyn. But I assumed May was more popular than she was. I thought British voters rather liked her stiffness and reserve. They may have told pollsters they preferred her to Corbyn, but it seems they don’t like her that much.

So, yes, I underestimated Corbyn’s appeal. I allowed my disagreement with his policies to colour my assumptions about what other voters would think about them. But I was not completely wrong. Labour came nowhere near being the largest party, and was even further away from winning a majority of its own. I still think another leader – goodness knows who, though – will be needed next time.

But the important thing for me is to understand my mistakes and to learn from them.

You can listen to John read and discuss his piece here.

