Before this year's London elections Cameron and Osborne let it be known that when Boris joined them for a private dinner in Downing Street, just months before he was due to face the voters of London, they asked to hear his plans for the looming battle with Livingstone. What they heard — a bit of bluster and a very thin policy prospectus — horrified the prime minister and chancellor. There is a certain irony in the architects of the Conservative party's inept, but very expensive, campaign for the 2010 general election accusing Boris of lacking any clear worldview or retail offer, in the policy jargon. But is there really any more to him than funny speeches and a hunger for power?

"I have no idea what he believes in other than himself," says a prominent Conservative. Above all it is clear that Boris believes himself to be a man of destiny. In the mid-1930s the prospect of Winston Churchill becoming prime minister was not taken seriously until circumstances changed. Boris, says a sympathiser, sees it in similar though less dramatic terms, and one must hope fervently that any moment of destiny does not include the need for military conflict. But it is perfectly possible that Boris's run for the Tory leadership in the middle of this decade would coincide with Britain attempting to work out, after the eurozone crisis, what a redrawn relationship with Europe will look like. To Boris, the idea of Britain as great global trading nation which has good but much less restrictive relations with Europe is appealing. That may be where British public opinion ends up too.

The most appealing aspect of Boris Johnson's credo is his view of government. It seems Rooseveltian (Teddy, not FDR) in its conception, something he shares with Michael Gove. Too many modern Conservatives now sound as though they hate government and all its works. Even if the state is shrunk, as it must be to create the space for private endeavour to flourish, there will still be a lot of government. Must it be talked of in abusive or wholly negative terms? 

Johnson is a free-marketeer but he is also comfortable with government using its clout to order large projects which are Victorian in the scope of their ambition. Instead of wasting years on Heathrow, and making life intolerable for those living in south-west London, he thinks it would be far better to create the best airport in the world with four, five or six runways and fast rail links into London from the edge of the Thames estuary. "Boris Island", which is much more likely to involve building on the coast than the construction of a new island, dwarfs David Cameron's rather limited plan to take 25 minutes off the journey time between Birmingham and London with a high-speed train line. "We have to have a new airport" he told New York magazine. "One of the only reasons I want to assume supreme power in England is to make sure that happens — for God's sake, don't quote me saying that."

As with everything involving Johnson there is a large element of risk involved. He may yet exceed the voters' capacity for amusement. His timings may be derailed by another economic crisis or the emergence of a strong Conservative rival. But don't bet against Boris.