One of the most inconvenient aspects of covering the Labour Party, for any aspiring writer, is thinking up new adjectives to describe the once proud faction’s descent into the moral and intellectual abys. I’m convinced I made my way through the standard ones, “catastrophic”, “ruinous” and “calamitous” for example, within months of Jeremy Corbyn assuming the leadership in 2015. I fear that, were it not for the thesaurus, I would have stopped commenting on the subject out of sheer vocabulary-based embarrassment.

Yet even by Labour Party standards the past week has been extraordinary. The revelation, via emails leaked to The Observer, that individuals close to the Labour leadership had been intervening in Labour’s internal disciplinary process destroyed any notion that it is truly independent or impartial. Laura Murray, an aide from Corbyn’s office, reportedly sought leniency for a Labour member accused of defending an anti-Semitic mural. Given Corbyn himself opposed the destruction of the alleged “artwork” in 2012 this did at least save a good deal of embarrassment. Officials representing Labour General Secretary Jennie Formby also opposed several expulsions over alleged anti-Semitism, despite them being recommended by the Party’s disciplinary panel.

Faced with pressure to react the Labour Party did, though in a manner that somehow made the situation even worse. Laura Murray, already facing criticism over apparent interference in the mural case, was sent to join the Labour compliance unit that investigates cases of alleged anti-Semitism. Putting a fox in charge of security at a chicken coop appears positively sensible by comparison.

The same day as her appointment it was announced that Ms Murray is facing legal action from Rachel Riley over allegedly libellous comments she made on Twitter. The Countdown star, who is herself Jewish, has been mounting an increasingly vocal campaign against anti-Semitism within the Labour Party. In doing so she has crossed blades not only with anti-Semites, but also with far more prominent figures who aim to excuse or downplay their actions. Quite why Riley, a TV host, is doing more to combat Labour anti-Semitism than most of the Party’s own MPs is a question they would doubtless prefer went unasked.

Leaving aside that we know she intervened in at least one case you would have to believe that Ms Murray would avoid discussing investigations with her own father, Andrew Murray, who will continue to work in Corbyn’s office. Andrew Murray, a communist party member until 2016 notable for urging “solidarity” with the North Korean regime, is the former chief of staff to Unite general secretary and key Corbyn backer Len McCluskey. He in turn is the former partner of Jennie Formby.

It’s astonishing, for a supposedly egalitarian movement, how many senior Corbynites turn out to have longstanding personal, even family, connections with each other. Sometimes it feels more like an episode of the Borgias then the leadership of a conventional political party. Perhaps that’s why intra far-left disputes are so fiery as they tend to at least partly take place within the family.

For anyone who’s been following the Labour Party’s increasingly concerning relationship with anti-Semitism it’s scarcely a surprise to discover its disciplinary process is neither free nor independent. When I spoke to a Labour press officer last year, following a tipoff from Labour Against Antisemitism (LAAS), they would give me precisely no information about the process. How many cases they were dealing with, what punishments were being meted out and even the size of their team turned out to be closely guarded secrets. It is however extraordinary to see just how blatantly those close to the Corbyn leadership were intervening.

What the case illustrates is why Labour is an institutionally anti-Semitic party, as opposed to merely a party with an anti-Semitism problem. This is the very top of the party directly intervening to downplay appalling abuse, not the ignorable rantings of some overzealous activist on an obscure left-wing blog. It’s now over two weeks since seven formerly Labour MPs broke away from the Party to form the Independent Group. Several on departing accused their former party of being institutionally anti-Semitic and racist.

Perhaps the most shocking thing about the defections, for me at least, is that I’ve yet to see a serious effort by either the Labour Party, or its media outriders, to refute the charge in detail. Plenty of efforts to change the subject for sure, and dust kicking to obscure the issue, but not the kind of full fronted defence, possibly backed by legal action, you would expect a truly aggrieved party to mount.

A Jewish Chronicle survey last autumn found 40 percent of British Jews would “seriously consider” leaving the country if Corbyn becomes Prime Minister. I have spoken to several who fall into this category myself, and it is hard not to be touched by their pain and anguish. Moderate Labour MPs must be aware they can stop this, anytime, by breaking away from the Party in sufficient numbers. Corbyn simply cannot became Prime Minister without the connivance of the centre-left. Should they continue to provide it they will bear almost as much responsibility for what follows as the most devout Corbynites. The hard left now control just about every lever of power within Labour, and there is no indication this is likely to change. Quite simply there is no longer a moral case for remaining within Jeremy Corbyn’s Labour Party.