“I will tear out this poison by its roots,” Keir Starmer said of antisemitism in his party, when he made his acceptance speech as Labour leader in April. Few colleagues doubted therefore that he would seize the earliest possible opportunity to make an example of someone – but by sacking his leadership rival, Rebecca Long-Bailey, he has reignited Labour’s civil war. Members of the Socialist Campaign Group of MPs, including John McDonnell and Richard Burgon, had been biding their time on the backbenches – sometimes making more strident criticisms of the government than Starmer’s, but remaining scrupulously loyal in public. Now one of their own has been ruthlessly removed, they will feel emboldened to make their voices heard more loudly. McDonnell, who worked closely with Long-Bailey as shadow chancellor, said he stood in “absolute solidarity” with her. Compared to some of the most egregious examples of antisemitism in the Labour party that have received publicity in recent years, Long-Bailey’s appeared to be a borderline case. She enthusiastically retweeted an interview with the actress Maxine Peake, in which Peake drew a link between Israel and the US policing methods that resulted in the death of George Floyd – calling Peake an “absolute diamond”. The first version of the article, in the Independent, said Amnesty International had suggested some US police forces had received training from the Israeli secret services, thus apparently legitimising the comment – though the sentence was later changed. One shadow cabinet colleague said their first thought was that Long-Bailey had probably not read the whole article, and was just endorsing its central thrust, that leftwingers should remain in Starmer’s Labour party. Momentum founder Jon Lansman, who is himself Jewish and remains on Labour’s national executive committee, said he had emerged from a party panel considering antisemitism cases to retweet Long-Bailey’s original praise of Peake. But Starmer wants to show that the days of debilitating debates about the finer details of what constitutes antisemitism are over. In stark contrast to Boris Johnson, for whom the whiff of corruption has not been sufficient to merit the sacking of Robert Jenrick, the appearance of antisemitism is enough for the new Labour leader. And he will know that the public do not engage with the details either – but will get the message that a high-profile party figure has been sacked over antisemitism. Just as the very public resignations of Luciana Berger and other Labour MPs despairing at their party’s record on antisemitism showed the public that Labour had a problem, Starmer will hope this sacking demonstrates that he is dealing with it. One ally of Starmer claimed Long-Bailey had form, citing a video of a rally that emerged during the leadership campaign in which she failed to challenge a member who attacked the “Israeli lobby”, which they claimed included Tom Watson and Margaret Hodge. Indeed, some of the most spirited clashes during the largely polite leadership race came over antisemitism. In February’s Newsnight debate, Emily Thornberry said she and Starmer had both raised antisemitism repeatedly in the shadow cabinet and called for regular reports on tackling it, adding: “I don’t think Rebecca did.” Long-Bailey shot back “I did, I think you’ll find”, prompting Starmer to warn: “Let’s not descend into scoring points.” But the party’s record on antisemitism, and the very public row it generated, is inseparable in the minds of many of Jeremy Corbyn’s allies from what they saw as the relentless internal war waged against his leadership from inside the party machine. A report prepared under Corbyn’s leadership for submission to the Equality and Human Rights Commission, and leaked after his departure, detailed a “hyper-factional atmosphere prevailing in party HQ” in the first year or more of his leadership. Party officials’ personal WhatsApp messages showed them referring to Corbyn and his team in insulting terms, and even expressing disappointment at 2017’s better-than-expected general election performance. The report claimed the party’s compliance department saw its central task as weeding out leftwingers who might support Corbyn in a leadership challenge – not methodically processing an escalating caseload of antisemitism claims. Against that backdrop, team Corbyn regarded media reports about antisemitism, and his failure to get to grips with it, as just another front on which his leftwing leadership was under siege. When Long-Bailey was sacked on Thursday, her supporters immediately saw it through the same lens: concluding that Starmer had seized the opportunity to purge one of the few remaining leftwingers from his frontbench. As far as policy goes, there is little evidence that Starmer is abandoning Corbyn’s legacy – though in the grip of a national emergency and with no general election due until 2024, there have been precious few policies at all. But in terms of personnel, many have been alarmed about what they see as the jarring contrast between Starmer’s message of “unity” during the leadership campaign and the comprehensive clearout of the Corbynite left he carried out once he got the job. One Starmer-sceptic also pointed out that Long-Bailey, who represents a leave-voting constituency, had been sympathetic to Brexit, during the bitter internecine battle over the party’s stance that raged throughout last year. Perhaps it didn’t help, either, that Starmer was visibly irritated last week when Boris Johnson wrong-footed him at prime minister’s questions by pressing him to say he thought it was safe for children to go back to school. Starmer’s allies insist he has worked closely with Long-Bailey on schools policy; but some more centrist Labour MPs have accused her of listening too intently to teachers’ unions, and not enough to parents, as she warned about the risks of wider reopening. For these reasons he may not lament her departure from the frontbench, but Starmer’s allies insist he would deal just as determinedly with claims of antisemitism even if they came from a close political friend. Chatter among the exiled Corbynites was already about whose actions will be singled out for censure in the EHRC’s report on Labour’s handling of antisemitism complaints. After Thursday, they can have no doubt how Starmer will respond.