The late Muhammad Ali said that if you think the same thing when you are 50 that you thought when you were 20, you have wasted the last 30 years. “When the facts change, I change my mind,” said John Maynard Keynes. If that’s good enough for an ultimate brainbox like him, it’s good enough for the rest of us.

Politicians notoriously have terrible difficulty admitting to changing their minds. They feel under constant pressure to be consistent, on message. The press beat them up if they change course, and their more doctrinaire supporters denounce them as traitors. Admitting to uncertainty is not in most politicians’ repertoire, the more’s the pity. U-turns are out of fashion. Politics is the poorer for it.

Sarah Wollaston’s switch from the leave to the remain side of the EU referendum argument isn’t a major event in itself. But it may nevertheless be a small event with larger consequences, and the Totnes Conservative MP had two precious assets on her side when she decided today to brave the wrath of west country Faragistes and the Daily Mail by changing her mind.

The first is that she is one of this parliament’s great independent-spirited figures, known for making her mind up her own way. For another, the facts are on her side. The leave campaign’s claim about Britain sending £350m to the EU every week, which it has never amended and which came through my own letterbox again on Tuesday, isn’t just misleading. It’s a lie.

So is the implication that, after Brexit, all that money would somehow be spent on the NHS, a subject on which Dr Wollaston, who chairs the Commons health committee, knows her onions. John Major skewered that part of the lie last weekend when he said that leaving the Brexiters in charge of the NHS would be like leaving a pet hamster with a hungry python.

Dr Sarah Wollaston defects from Vote Leave to remain campaign Read more

Wollaston isn’t the only politician to change her mind in this campaign. Jeremy Corbyn, lifelong opponent of the EU, has done it too. But Wollaston’s honesty and Corbyn’s grudging sense of duty to his party stand in sharp contrast to some of the more disreputable changes of political stance in Conservative ranks during this EU campaign.

About Boris Johnson’s views, no one now needs much illumination. The man will say anything. He is a first-order ego with a lifetime fail in personal loyalty.

His more senior Brexit campaign colleague Michael Gove has been travelling a more interesting journey these past few weeks. Be in no doubt that it is the justice secretary, not Johnson, who is calling the shots in the leave campaign.

Gove chairs the meetings and sets the agenda for leave. His acerbic former adviser Dominic Cummings, long loathed by David Cameron (the feeling is mutual), is the campaign director. Two other battle-scarred Gove lieutenants, Henry de Zoete and Henry Cook, play key roles.

All of which raises two larger questions about Gove. The first is how someone whose self-image and public reputation is as an intellectual conservative, a self-described moderniser fascinated by openness, logic and ideas, can have become so wholly converted to a backward-looking, populist campaign that is now almost wholly focused on frightening British voters out of the EU over the issue of immigration.

And that’s without even mentioning the effect that the attacks mounted on colleagues by this once scrupulously loyalist cabinet minister will have on his increasingly divided party. Gove has come a long way from that elegant but restrained initial statement of rejection of government policy at the start of the campaign.

It’s more than a U-turn. It’s the U-turn of a man who has got himself trapped in a revolving door

As Gove himself might put it, it is as though he, in US Republican terms a Rand Paul-style doctrinal conservative, has morphed in the space of a few weeks into a Donald Trump-style scaremonger. The campaign on which Gove is now embarked is at odds with much of what he once stood for. The campaign is narrow, nasty, dishonest and driven by polling, while apparently spurning any of the old Govian high-minded argument. It is almost unrecognisable as the work of a man whose occasional willingness to give questioners the run of his mind meant that an hour in his company was always one of the more fascinating experiences in politics.

The strangest aspect of this shift is that Gove has for so long been one of the prime defenders of a liberal, open-door immigration policy in Cameron’s cabinet, even to the extent of arguing at one stage that immigration should be fully marketised, with UK passports for sale on the global market.

Ever since 2010, Gove has consistently argued in government against immigration controls, making alliances with his fellow economic liberal George Osborne – now his bitter EU opponent – against home secretary Theresa May’s attempts to tighten controls. So to hear Gove saying, as he did in an interview with Robert Peston, that a Brexit Britain would reduce migrant numbers to tens of thousands is breathtaking for its audacity – it is a personal volte face – and it’s dishonesty: it isn’t going to happen. It’s more than a U-turn. It’s the U-turn of a man who has got himself trapped in a revolving door.

What can explain it? In part, perhaps, the answer is that Gove is always happier with the big sweep of a policy idea than with the practicalities. That was a charge made against him during his time as education secretary and it is sometimes made against him at the ministry of justice. Like some of his fellow newspaper columnists, he may prefer to be carried away with an idea than to interrogate it too carefully.

But the other thought is that the campaign is proving to be catnip to Gove’s personal ambitions. The rightwing libertarian in him may have embraced the leave campaign as a Lutheran crusade against a bureaucratic leviathan. But the politician in him has the scent of power in his nostrils.

Gove has often been thought of as the kingmaker in the next Tory leadership contest. Now, though, he may have his eyes on the crown itself, whatever the effect on either the Tory party or Britain’s migrants.