A number of Corbynsceptics are very angry about my analysis of the ongoing row over the International Holocaust Remembrance Alliance definition of anti-Semitism, which has taken another turn after the MP for Dudley North, Ian Austin, had disciplinary measures brought against him.

My take is that for the bulk of Labour’s Corbynsceptics it is increasingly hard to see how they are better served by remaining within the Labour party. The criticism from organised Corbynsceptics – including Richard Angell, the director of Progress, one of the two major organisational centres of Corbynscepticism within the Labour party – is that actually they should “stay and fight”. Elsewhere, and less publicly, some Labour MPs are increasingly of the opinion they should leave. Who is right?

I take the view that political analysis should, for lack of a better phrase, be “protagonist-led”: the assessment should be driven by whatever the subject wants to achieve and their likelihood of doing so by the methods they have chosen.

That doesn’t mean that political analysis shouldn’t be critical of its subject. But it should start from the perspective of what the subject actually wants to achieve rather than grading them against some Platonic form of a politician. A lot of critical commentary on Jeremy Corbyn is based around his failure to be the best version of Yvette Cooper. I am not convinced this is a useful yardstick as their skillsets are so different that it’s a lot like assessing the Arsenal squad on their chances of winning Wimbledon. (It’s also not like there is a shortage of opportunities to be critical of Corbyn’s failures to be the most effective version of Jeremy Corbyn.)

So to understand what Corbynsceptics should do, we need to start by looking at what their aims are. Corbynsceptics within the Labour party have two objectives: the first is to survive as a political tendency during a time in which Jeremy Corbyn is hegemonic and likely to remain until at least the next election. The second is to somehow reach a point where they can displace Corbyn and Corbynism as the dominant force on the British left. That runs through either forming a new party to replace Labour from outside or winning the votes of at least some of the six in ten Labour members who voted for Jeremy Corbyn in 2015 and 2016 from the inside. (In reality, due to Corbynsceptic members departing and pro-Corbyn members joining that is probably more like eight in ten now, but the essential calculation remains unchanged.)

For “staying and fighting” to succeed, it requires an awful lot of staying and very little fighting. Most of the people who voted for Corbyn are - this shouldn’t be surprising or controversial - fairly supportive of the Labour leader.

That means winning them over requires a significant degree of fealty towards the Labour leadership, one that many Corbynsceptics have been neither willing nor able to stomach. And if they can’t do that, their best – I am not saying I think it is a particularly good option nor one that has a level of success – is to split.