I’m convinced Ruth Davidson could be the next prime minister, even if the bookies favour Boris Johnson

The leader of the Scottish Conservatives said: ‘I’m not sure the party would be happy with a drippingly wet, pro-immigrant lesbian Scot.’ But it could choose her all the same

The betting market favours Boris Johnson, David Davis, Amber Rudd and Ruth Davidson (PA)

Normally, I would agree that speculation about the next leader of a party is fairly pointless, although that has never stopped me. But Theresa May could go at any moment and we are in the odd position of knowing that she is most likely to be replaced before the next election, and so the identity of her successor is of pressing interest.

The last time we were in this position, Tony Blair had announced he would be standing down, but it was assumed – despite occasional flurries about David Miliband, Alan Johnson, John Reid and Charles Clarke – that Gordon Brown would be his successor.

This time there is no such certainty. There are currently four or five candidates with a good chance, and the way politics is, it could be someone else entirely. I say “four or five” because I am not sure whether to include Jacob Rees-Mogg as a serious contender, but more of him later. The other four are, in the order by which they are favoured by the betting market, Boris Johnson, David Davis, Amber Rudd and Ruth Davidson.

There was a lot of speculation about Davidson at the Conservative conference in Manchester, although she told a Social Market Foundation fringe meeting, “I’m not sure the party would be happy with a drippingly wet, pro-immigrant lesbian Scot.” Those are of course precisely the reasons the party should choose her: she is their best hope of countering Jeremy Corbyn’s appeal, especially to young voters.

By the end of the conference, most Tories seemed to have decided it was all too difficult. She’s not an MP, she hasn’t been a minister, and it would be too late to install her before the next election. So they went back to worrying about Brexit instead. But the succession question won’t go away, and since the conference I have come across three more reasons for thinking she could do it.

First, the Tory party seems surprisingly ready for a drippingly wet, etc, leader. A YouGov poll of party members last month gave her a better “good leader” rating (58 per cent) than Boris Johnson (56 per cent) and put her just behind him, by 23 per cent to 19 per cent, as their first choice to take over from May.

I have also seen a ComRes survey of Tory local councillors, the pragmatist activist core, in which Rees-Mogg, Davidson and Johnson were almost level on 20, 19 and 18 per cent respectively. (The poll of a random sample of 550 councillors in England and Wales was carried out 8-25 September, but has not been published before.)

The high score for Rees-Mogg is interesting, in the Chinese curse sense of the word, and reflects the strength of the ideological wing of the party, but I thought it more significant that councillors in England and Wales think a Scottish drippingly wet, etc, is the key to the next election.

The second reason for thinking she could be the next prime minister comes from a conversation with Andrew Adonis, the Labour former cabinet minister, chair of the National Infrastructure Commission and campaigner against Brexit. He said to me: “The best test, and the best training for a prime minister is to be leader of the opposition.” Being a minister helps, he said, but the best single test is leading the opposition. It was part of Theresa May’s problem, although it was only found out during the election campaign, that she had never had that experience.

Davidson has been leader of the opposition in Scotland, with some success. This may not be as testing as the Westminster equivalent, but in Adonis’s view it goes a long way to making up for her lack of experience as an MP or a minister. The leader of the opposition has to take the argument to the leader of the government, face to face and across the whole range of policy. Davidson has held her own with energy and quickness of mind against Nicola Sturgeon, the First Minister, in the Scottish Parliament, who is a formidable opponent. And she has led a UK election campaign in Scotland, in which 12 new Tory MPs were elected.

Adonis’s theory is a corollary of his argument in this month’s Prospect that, in all two-horse national elections in stable democracies, “the best leader wins and nothing else matters”.

Naturally, he overstates his case slightly for rhetorical effect, but I think his argument is essentially true. Policies are less important than how voters assess the personality of those who espouse them. He quotes Jonathan Freedland’s fine aphorism: “People do not believe in ideas: they believe in people who believe in ideas.”

The third argument for Davidson is the Jacinda Ardern effect. Many people think it would be too late to get Davidson into the House of Commons after the 2021 Scottish Parliament elections to fight a 2022 UK general election. But Ardern was elected leader of the New Zealand Labour Party on 1 August this year, seven weeks before the election on 23 September. She closed the ruling National Party’s 20-point lead in the opinion polls, and next week takes office as prime minister after securing a deal in a hung parliament with Winston Peters’ New Zealand First party.

So it could happen. It may be much too early to try to imagine what might happen, on the other side of the great mystery of Brexit, in four years’ time. But that is half the fun of politics.