Jeremy Corbyn was given an easy ride on incoherent policies because no one thought he would win

It is possible that some people voted Labour because they didn’t think Jeremy Corbyn would win. There may have been some who were opposed to Corbyn but liked their local MP, or wanted to bring Theresa May down a peg or two. They might have thought it was safe to vote Labour because the opinion polls suggested that Corbyn wouldn’t be prime minister.

As Peter Kellner, the former president of YouGov, said at a recent convocation of psephologists: “Because the polls got it wrong, the public got what it wanted.” That is, a Conservative government unable to implement most of its policies, with Corbyn kept out of No 10.

It is hard to know how many anti-Corbyn Labour voters there were. YouGov found that 6 per cent of Labour voters said the local MP was their “main reason” for voting as they did. We reported this as “just” 6 per cent, but if they had all voted for another party or stayed at home, the Conservatives could have won a majority of 40 seats.

My guess, though, is that, if the polls had shown a closer contest, most of these voters would have stuck with Labour. They may not have been enthusiastic Corbyn supporters, but I suspect it is mostly newspaper columnists who are capable of the sophistry needed to vote Labour while hoping for a Conservative government.

That said, there was another way in which the poll-driven consensus that Corbyn wouldn’t win helped to boost the Labour vote. It was that Labour policies were subjected to less scrutiny than if journalists thought there was a real chance they could be implemented.

This meant John McDonnell, the Shadow Chancellor, was able to go through the last three weeks of the campaign saying the party’s policies were “fully costed” on the basis of two sides of A4. The Institute for Fiscal Studies said, politely and neutrally, that the costings document didn’t remotely add up and yet Corbyn and McDonnell were never put under much pressure on it. Partly, this was because the Conservatives failed to cost their own manifesto, and because May wouldn’t allow Philip Hammond to campaign on managing the economy. But mainly, it was because few people expected a Labour government.

The contradictions in Labour’s policy on the gap between rich and poor received little attention. The manifesto complained that “inequality has ballooned”, which is debatable, but the net effect of Labour promises would have been to increase it. Abolishing tuition fees, extending free childcare and free school meals to the middle classes and investing in railways would all tend to benefit the better-off. Those spending promises were worth at least three times more than the modest sum earmarked for social security, and the manifesto’s drafters forgot to say anything at all about the cash freeze (that is, real-terms cut) in benefits, which will take billions from the working poor.

Just as puzzling was Labour’s case for renationalisation. It is easy to see the argument for the promise to abolish tuition fees, even if you think it was simply buying votes. But what is the rationale for public ownership? Corbyn once had a rough time in an interview with Andrew Neil in which the Labour leader tried to argue that the government could buy back the National Grid and the Royal Mail without increasing its debt.

Yet Corbyn and McDonnell were never asked why it was a good idea. Do they think railways, energy companies and other natural monopolies would have been more efficient if they had never been privatised? Does that apply to BT and BP? If not, why not? And why doesn’t Corbyn want to restore the old Clause IV of Labour’s constitution, which committed the party to “the common ownership of the means of production, distribution and exchange”? After all, he opposed getting rid of it in 1995. So many interesting questions, and yet such a lack of curiosity about the party’s answers during the election campaign.

Again, on Brexit, the manifesto contradicted itself. Although some Remainers criticised Corbyn for offering the same policy as the Government – out of the EU single market and ending the free movement of people – the manifesto contained a paragraph that implied the UK might never leave the EU under a Labour government. It said: “We will reject ‘no deal’ as a viable option.” This suggests that, if a deal could not be agreed, the UK would remain a member until it could be.

In each case, Corbyn managed to create a general impression – of caring about poverty, of being against “privatisation”, and of being a little less Brexity than the Government – without ever being probed on the details.

As Andrew Harrop of the Fabian Society argues in the summer edition of the Fabian Review, the party will not be able to get away with that next time. “Next time Labour writes a manifesto, it needs to think harder. [It] needs fewer easy slogans and more nerdy homework.” The party will not be able to hold on to its votes and to gain the extra votes it needs to win unless it does the hard work of devising policies that can withstand the scrutiny of an election campaign that people think it might actually win.