He has protean strengths and is a proven winner. But it's too early to say that Boris should be the next Tory leader.

By Paul Goodman
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The sum of Lord Ashcroft's stupendously sizeable poll about Boris Johnson this morning - Ashcroft Polls will soon be taking samples from the entire country - is that the London Mayor is more popular but less rated than the Prime Minister. Our proprietor writes on this site today -

"When asked who would make the best PM, each of the three party leaders or Boris, David Cameron came out narrowly ahead on 33 per cent, two points ahead of Ed Miliband, four points ahead of Boris and 26 points ahead of Clegg. Among Conservatives, Cameron was the clear winner over Boris, by 81 per cent to 18 per cent."

Stephan Shakespeare wrote recently on this site about a YouGov poll on Boris, which found that "30 per cent of the intending voters in this sample said they would vote Conservative with Cameron in charge, and 36 per cent said they would vote Conservative with Johnson".

However, as Shakespeare himself pointed out, polls that ask how people would vote today were the party leaders different are highly speculative.  His polling converges with Lord Ashcroft's in finding that Boris scores well with UKIP voters, despite his shape-shifting views on Britain's EU membership.

All in all, Boris has protean strengths, some weaknesses and a proven track record as a Conservative election winner in what is essentially a Labour city - as well as a marvellous sense of the challenges facing ever-pullulating London.

But there is no evidence that he is better placed to succeed David Cameron than Michael Gove or  Theresa May or the unexpected candiate who pops up in leadership elections and usually wins.  Furthermore, the timing of a Boris Commons re-entry and a post-2015 poll don't fit neatly: he remains Mayor until 2106.

And finally, the whole caboodle may never arise, since Cameron could well lead a re-formed Coalition after the next election.  I end in oleaginous agreement with the proprietor: the case for Boris as leader isn't proven, and it's too early to start making it.