One of the ways you can tell that the media really does know that Miliband is the most likely next prime minister is that there is much more speculation about Cameron’s successor as Tory leader than about who the next Labour leader will be. The papers just don’t want to say it. The idea of Miliband as front-runner will legitimise him. And their whole strategy is about delegitimising him.

I always find it fascinating, though, to look at those speculations. What they reveal is a huge amount about who the media thinks is ‘good’. And that tells us much more about the papers than it does about the politicians they (we, I suppose) are judging. In this context, I have often asked a question: why is Boris Johnson seen as a likely next Tory leader, but Carwyn Jones never mentioned as a viable future Labour leader?

The only difference between the two men is that one has significant powers and has used them, and the other doesn’t and hasn’t; one is the person in their party with by far the most executive power, the other isn’t. Of the two, it’s the First Minister of Wales who is the more impressive and serious politician by almost any sensible measure. Boris is little more than a glorified local council leader with silly hair.

This principle extends further though. This summer, there’s a very good chance that the Conservative party will be back in opposition and looking for a new leader. It will have failed to have won a majority in a UK General Election for 23 years. By the likely next election, that will be 28 years. If the Tories had any sense at all, they would think very carefully about what that means. The last time a party previously accustomed to government could have said that is the Liberal party in 1932.

In this context, for them to choose another old Etonian Oxford graduate from the South East of England would be an astonishing act of self harm for the party in the long term. Of course, it’s possible that Mr Johnson would keep the show on the road for a few fleeting years. But it would be by clinging to a disappearing past, not by laying claim to the future.

No. If the Tories wish to survive (which, as someone who has never voted for them, is perhaps none of my business) then they need to look further afield. And for them, there is another consideration too. Where I grew up, what it says on the ballot papers is “Conservative and Unionist Party”. And if they really believe in that (as someone who voted yes, perhaps that's not my buisiness either), then the reasonable likelihood that they will have no MPs from the second biggest nation in the union after the election should trigger in them some serious soul searching.

In that context, if I were a Tory party member, then I would have been watching tonight’s Scottish leaders’ debate with some interest. Because it seemed clear to me, as someone who would never come close to voting Tory, that Ruth Davidson, leader of the Scottish Conservatives, put in a much better performance than David Cameron did the other night. And this wasn’t because it was an easier contest – I think every party but UKIP and the Lib Dems was better represented in tonight’s Scottish debate than in the UK leaders’ debate.

Ruth Davidson, for those who don’t know her, is not the stereotype of a Tory leader. She is a 36 year old kick-boxing lesbian from Glasgow. She’s admired across the political spectrum by people who can’t stand her party as well as those who love it. She’s articulate, intelligent and holds her own in one of the toughest political contexts for her party in the UK. Being a Tory in Oxfordshire is easy. Being a Tory in Glasgow takes some doing.

There are practical questions. She is an MSP, not an MP, and there isn’t exactly a Tory safe seat in Scotland she could just win in a by-election. On the other hand though, it would send a pretty powerful signal about how serious the Tories are about the union if they were led for a period from Holyrood and represented in Westminster by their deputy leader. As Salmond ran for First Minister from outside the Scottish Parliament in 2007, Davidson could run for PM in 2020 (or, as some speculated about Mandelson in 2010, she could lead from the Lords until 2020, then resign her peerage and run as an MP).

The second obstacle is that anyone sensible in the Scottish Tories understands that they only ever came close to winning elections in Scotland when they had their own independent Scottish party, the Scottish Unionist party. In a sense, though, this provides another (and perhaps more viable) potential solution to the previous question. The Tories across the UK could split (as they already have in effect, with the Unionists in Northern Ireland). They could chose a leader in England and Wales as well as Scotland, but they could run in 2020 being clear that their candidate for Prime Minister is Ruth Davidson, not the English leader – just as the CSU leader has on occasion been candidate for German Chancellor rather than the CDU leader.

The third obstacle is that I suspect, post-referendum, the Conservatives will never accept a Scottish leader. They are retreating fast into English nationalism. Even Polly Toynbee has suggested that a Scottish Prime Minister or party leader is now impossible. This is probably true, and it’s the surest sign that the union wasn’t saved on 18th September last year, but put on life support.

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