Each week it seems to get worse, as Jeremy Corbyn’s worst week succeeds the previous one. Discontent about his leadership turned into open civil war yesterday when the Party Leader wrote to all of his MPs explaining he cannot support UK military action in Syria. Clear leadership you might think? Except the letter followed just hours after a long Shadow Cabinet meeting during which the vast majority of Shadow Ministers said they wanted the Party to back the action, and the meeting adjourned until Monday when it would be given further consideration.

In this context, Corbyn’s decision to pre-empt the second meeting with the letter is a staggering one. Shadow Ministers are said to be furious and more determined than ever to back the Government in the vote which is expected by the end of next week. A “free vote” on the Labour side seems to be the only way out of the impasse but where, Corbyn’s critics ask, is the credibility of a party that cannot even reach a common position on the fundamental question of war and peace?

Until a few weeks ago, Labour MPs had reconciled themselves to the fact that they were stuck with Corbyn until at least 2017. Paris, its fall-out and his response has changed all that. Some MPs smell blood already, and a bad result in the Oldham West by-election next week could even see a move against the Leader before Christmas. Just two months into the job, Jeremy Corbyn is already staring down the barrel.