Is Boris Johnson preparing to quit?

"Is Boris preparing to flounce out of the cabinet?"

Not my question, but that of one of his senior ministerial colleagues.

Why could that be?

Exhibit A.

In this morning's Cabinet, he is hijacking Jeremy Hunt's update about how hospitals are coping with the winter pressures with a headline grabbing and overtly populist demand for the Treasury to find an additional £5bn a year of health spending - which would be a modest down payment on the £18bn ("£350m a week") he pledged during the EU referendum campaign.

Theresa May won't be amused. Hunt can't be sure if Johnson is friend or foe.

But it is the kind of typical Borisian intervention that says to his backbench colleagues "if she's too timid as PM, look what I would do".

Exhibit B.

The government is on course for the kind of softish Brexit - membership of some kind of customs union, the kind of regulatory convergence with the EU that should deliver cheaper trade with the EU but constrains the UK's lawmaking autonomy - that Johnson and Gove fear may be worse (in their terms) than being a member of the EU.

The logic of where Parliament's centre of gravity resides is driving May in that direction.

And if that is where the cabinet arrives, Johnson and Gove will feel thoroughly sick.

Conclusion.

If Johnson feels his best chance of becoming leader would be by first preparing the ground from the back benches, the principled reason for resigning - in order to win back the support of sceptical colleagues - would be because the Prime Minister is offering the wrong kind of Brexit.

And his personal manifesto pledge would be the late delivery of that £350m for hospitals!