If the Conservatives are existentially threatened by four-party politics – as they are – then so is Labour, arguably more so.  It was fourth, on 18 per cent, in a recent poll.  On Brexit, London-leaning Remain pulls the party one way, the Leave-voting provinces another, Remain-inclined Scotland another still.

And that is only a snap summary: out there in Leave country, Labour is losing votes to the Liberal Democrats and Greens as well as Brexit Party and, in some places, to the Tories.  Not to mention independents.  To get a flavour of how broad and deep the party’s problems are, have a look at Harry Phibbs’ tour, on this site each Friday, of May’s local election results in each region.  Or ponder Ian Warren’s stark conclusions.

No wonder Labour is consumed by splits over a second EU referendum.  But the party’s strategic position is so conflicted that it is in terrible trouble either way.  The origins of these problems lie much, much deeper: in the alienation of many left-wing parties throughout the western world from their traditional working class base – driven by identity politics, globalisation and mass immigration.

Meanwhile, Jeremy Corbyn’s ratings are worse that Michael Foot’s. And the conflict between the socialist instincts of his inner circle of advisers, who are hostile to a second referendum, and those of leading Shadow Cabinet members, who favour it, are eating away at his position.  The most striking aspect of the recent Times report about the party was about Labour’s policy, not his own health.

“According to one source: “Katie got up…and screamed at Jeremy, ‘We’re not doing that, we’re not selling out our class.’ He just sat back terrified.”  The cause of the dispute was Corbyn mulling the case for a second referendum.  “Katie” is Katie Murphy, his Chief of Staff – one of the “Four Ms” who make up that circle: herself, Len McCluskey, Andrew Murray and (inevitably) Seumas Milne.

Is it a concidence that this recent spate of claims about Corbyn’s health were circulated?  Or that John McDonnell doesn’t deny saying that Labour’s Brexit policy is a slow motion car crash? Or that he and other leading London-based MPs – Keir Starmer, Emily Thornberry, even Dianne Abbott – are in open conflict with those advisers?  Or that we read today of Labour about to take another fearful media pummelling over anti-semitism?

The advent of Boris Johnson as the next Conservative leader, and the prospect of a general election over a No Deal Brexit, seems to be galvanising Labour’s internal debate.  Expect further pressure, first, on the Four Ms and, then, on Corbyn himself.  In these helter-skelter times, one can’t simply assume that he will lead Labour into the next election: every assumption must be questioned.

Mind you, whether he is replaced (by Rebecca Long-Bailey, or a more Remain-friendly Labour leader, or whoever)  or whether he hangs joylessly on, we dare to make a prediction.  That whatever happens, McDonnell will be at or near the top, flourishing like a green – or is it red? – bay tree.