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A couple of weeks ago, I had a drink with one of Boris Johnson’s classics tutors at Oxford University, and asked him about his pupil’s chances of making it to Downing Street. “Capax imperii nisi imperasset...” he said.

As Boris will know, his old tutor was echoing the Roman historian Tacitus on the Emperor Galba: “He was up to the job of emperor as long as he never became emperor.”

That is the question on Tory lips this week at the Birmingham conference. Can Boris become emperor – or is he doomed to become the eternal jester of the Conservative Party?

His reception this week at Birmingham New Street Station was near-ecstatic – hundreds of activists cheering, “Bo-ris! Bo-ris!” as he got off the train. It’s hard to think of any other...