Gove is a genuine leaver though. I reckon he knows that Boris isn't, and doesn't trust Boris. Johnson's participation on the leave side was all about project Boris, and its gone wrong, because he won a vote he didn't intend doing. It's like a script from yes Prime Minister. The British have a fine tradition of amateurish endeavour that ends in farce. This comes straight out of that play book
Cameron had given notice that he wouldn't a serve a third term. He was likely going to announce he was stepping down in the autumn regardless of the result. The critical mechanism is the way that the Tories select their leaders though. Only two can go forward to the final ballot of the Tory party membership. Boris fancies his chances of winning the party membership, but he's more flakey on the parliamentary party. He needs to win enough of their support in order to get him onto that final ballot. This is his bigger hurdle
Now if Cameron steps down having won the referendum, one of the candidates is going to be George Osborne. That seals the continuity Cameron slot, and the Remainers. There's only one vacancy left. We reckon there's about 100+ Tory MP's who are leavers. This might be a minority, but 100 MP's is enough to lock up second position and a place on that final ballot. If Boris joins their camp and loses gallantly he's assured his place in the run-off. This is the big quandary for him. If he doesn't join the leave campaign, someone else who emerges as the champion of 'leave' inherits this constituency instead of him, and in all likelihood denies him a place in the final two. In essence he calculates that he has to fight for leave if he's to achieve his personal ambition of Downing Street. He has no choice
He then reckons he can beat Osborne on the wider membership, but will then feign indignation at having his hands tied by the referendum result that came back in favour of remain. Shucks! But since he was never a leaver anyway he's not bothered. He's achieved his goal and at no cost to his policy position
There is no shortage of evidence of Boris having adopted pro-EU positions or having made pro-EU statements. Similarly, whereas all the other leavers announced their intention to campaign for a vote within 24 hrs, Boris spent about a week weighing it up. Any committed leaver would have made that decision straight away. Basically he was calculating how it affected his more pressing priority, the prospect of being Prime Minister by Christmas
In the finest traditions of farce though, he's cocked it up. He's ended up not only winning and taking us out of the EU in pursuit of his own ambition, but in doing so he's likely to lose the leadership election too as the party seek someone who is better placed to negotiate a soft landing then one of the Brexit architects
It's little wonder that after having visited London and Brussels this week to take soundings, US Secretary of State John Kerry said this
“I think there are a number of ways (to walk back the result). I don’t, as secretary of state, want to throw them out today. I think that would be a mistake. But there are a number of ways.”