Boris Johnson is no more in favour of withdrawal from the EU than Jeremy Corbyn or John McDonnell is opposed to such withdrawal.
(Michael Gove may or may not be, but he is in any case yesterday's man in politics, and waiting for an editorship to come up somewhere.)
The difference is that no one holds Corbyn's or McDonnell's stance against him. There is a certain sense of disappointment, but no more than when Corbyn appointed certain people, and not certain others, to the Shadow Cabinet.
Whereas Johnson's stance will mean, either that he will have attempted to prevent a famous victory on the part of David Cameron, or that he will be liable to be blamed for having denied Cameron that victory, unlike "even Jeremy Corbyn".
But Johnson seems to think he can become Prime Minister in this Parliament, when that office will be filled on behalf of this country's 64,716,000 people, who have a median age of 40, by the 149,800 mostly elderly members of the Conservative Party.
Johnson ought therefore to declare his opposition to any further intervention, of any kind, in Libya, and he ought to challenge the Official Opposition to table a Commons motion or amendment to that effect.
With the promise that he would vote in favour of that motion or amendment, as would anyone who wished to be identified as a supporter of his.
He might or might not believe in that, either. But so what?