It seems the man with the Mandela placard is seen as no more trustworthy or principled than Boris Johnson. An Opinium poll published over the weekend found that less than a quarter of the public thinks Corbyn is “trustworthy”- a lower share than Johnson – and 36 per cent find him principled, the same as the prime minister.

It’s quite an achievement. Johnson, after all, drafted an article backing Remain days before coming out for Leave. His venality and lust for power are infamous.

Jeremy Corbyn is meant to be his antithesis – the principled backbench rebel who shunned all chances at political advancement in favour of pursuing his own unfashionable causes.

Corbyn’s ratings on every other front are terrible. Only 16 per cent of people think he is “best to negotiate with the EU” – fewer than one in six. Less than a fifth think he is a strong leader and able to get things done. Only one in five say he “represents what most people think” – quite the failing for a man who is meant to stand for the people Westminster forgot.

This is an extraordinary disintegration for someone whose reputation is built on honesty and principle – “straight talking, honest politics” – fighting someone known for his lack of either.

Should I vote Labour? Corbyn's biggest policies explained Show all 9 1 /9 Should I vote Labour? Corbyn's biggest policies explained Should I vote Labour? Corbyn's biggest policies explained Brexit Labour is committed to leaving the European Union but would have different negotiating priorities to the Conservatives. It has said it would have a “strong emphasis” on staying in the single market and the customs union. German Chancellor Angela Merkel and leading figures in Brussels have been unambiguous that membership of the single market is impossible without free movement. PA Should I vote Labour? Corbyn's biggest policies explained Immigration The party would drop “bogus immigration targets” but move to a managed system of migration favoured by many leave voters. It has said this “may include employer sponsorship, work permits, visa regulations or a tailored mix of all these”. Getty Should I vote Labour? Corbyn's biggest policies explained The Economy Labour’s manifesto commits to balance government spending with the amount raised by taxation, which can mean little more than significant tax increases. The greatest burden will fall on higher earners but they cannot meet demand on their own. It has also promised to bring rail companies back in to public ownership and cap fares. The party would also renationalise Royal Mail. It also promises a “transition” to publicly owned energy. Peter Byrne/PA Should I vote Labour? Corbyn's biggest policies explained Tax No one earning under £80,000 would pay any more in national insurance or income tax. It would raise corporation tax, from the current low of 19p to 26p. This higher rate would still be a competitive internationally, but the government is currently fighting hard to attract business in the wake of Brexit and they say a low corporation tax rate is crucial. Labour would also lower the top, 45p income tax threshold to £80,000. In theory, this could raise £7bn, but only if higher earnings did not decide to move abroad. Reuters Should I vote Labour? Corbyn's biggest policies explained NHS Labour has promised more money for GP services, free hospital parking for patients, staff and visitors, and to take a million people off NHS waiting lists by guaranteeing treatment within eighteen weeks. These promises will be expensive to keep, and there is no certainty that the party’ s commitment to raising taxes on higher earners, increasing capital gains tax and reversing cuts to corporation tax will be enough to meet the need. PA Should I vote Labour? Corbyn's biggest policies explained Education The party has pledged to abolish university tuition fees and reintroduce maintenance grants and give free school meals to all schoolchildren. PA Should I vote Labour? Corbyn's biggest policies explained Housing Labour’s manifesto commits to building 1m new homes, and would introduce controls on rent rises for private renters. It would also scrap the so-called bedroom tax. Getty Should I vote Labour? Corbyn's biggest policies explained Environment Labour would ban fracking, but, crucially, also supports new nuclear projects. It would also introduce a new Clean Air Act to deal with illegal air quality Getty Should I vote Labour? Corbyn's biggest policies explained Defence Its manifesto says it is committed to the NATO target of 2 per cent spending on defence. It is also committed to the renewal of Trident, even though Jeremy Corbyn has spent a lifetime campaigning against it. AFP/Getty Images

The veteran socialist has largely struggled to win over the British public since unexpectedly becoming Labour leader in 2015. But in the early days, despite a full blooded media onslaught against him, it was common to hear people say that whilst they didn’t agree with him, they respected how he stood by his principles.

Brexit has put paid to that. Britain’s Leave vote was always a challenge for Labour, one that any leader, drawn from any wing of the party, would have struggled to rise to. But the quiet triangulation that saw Labour through the 2017 general election has become increasingly blatant and absurd – and voters have noticed.

Having taken so long – via so much public flip-flopping – to commit to a second referendum, the party has pulled off the unenviable achievement of sounding like a pro-Remain party to Leave voters, while coming across as pro-Brexit to angry Remainers. When people don’t trust the leader, they’ll fill in the blanks for themselves.

Corbyn’s supporters argue that we’ve been here before. The 2017 election campaign saw an unprecedented turnaround in Corbyn’s personal ratings; such a recovery had never happened before during a British general election. Aided by Theresa May’s disastrous manifesto and insipid campaigning style, Corbyn was able to get on the front foot while focusing on his political passions – railing against poverty, inequality and austerity. Voters who saw him for the first time without the “guidance” of negative press coverage flocked to Labour.

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Corbynites are effectively betting the house that lightning strikes twice – not just the House of Commons in fact, but their entire political project.

Corbyn’s leadership represents the best chance socialists like John McDonnell will ever have of winning power and transforming Britain’s economic model. It is a chance they never dreamed they would get before the dramatic Labour leadership election in 2015.

But if an election is held before Brexit is passed, it will be difficult for Labour to focus voters’ attention away from the Leave-Remain divide. Johnson may by then be shedding centrist votes to the Lib Dems, but a late switch to unequivocal support for a second referendum could be too late for Labour to hold its own fragmenting coalition of voters together.

Johnson, for his part, has secured a “Boris Bounce” in the polls, squeezing Nigel Farage’s Brexit Party without shedding too much support to the Lib Dems. Yet the resulting Tory leads are smaller than those enjoyed by past leaders in their honeymoon periods – and May was unable to convert her yawning leads over Corbyn into electoral success.

Will Johnson suffer a similar fate? He can still plunder more support from the Brexit Party, though whether this just piles up votes in existing Tory heartlands remains to be seen. Labour, for its part, faces a huge fight to squeeze the Lib Dems (or vice versa) for anti-Brexit votes. There is little sign of a “Remain Alliance” between the two parties.