[It is] perfectly possible to be critical [of EU shortcomings] and still be convinced we need to remain a member - Jeremy Corbyn

He has long lived in a milieu where it is de rigueur to acclaim the Irish Republican Army as freedom fighters (not a popular view in much of working-class England and Scotland, where many families have sons and cousins who served in the army in Northern Ireland).

I are very concerned, however, to make sure there can be open and proper debate about Israel and its foreign policy, and about the future for Palestinian people. Hence there has to be that space for debate, you cannot shut that down. But it can never, ever be conducted in an anti-Semitic way.

Corbyn's Labour Party did not lose the 2019 general election because of the Salisbury poisonings alone—but they were a critical moment that embedded the image of Corbyn as weak and foolish.
This was driven almost entirely by Corbyn and his team, not by the Labour Party as a whole. Throughout the affair, Corbyn seemed more determined to protect Putin's reputation than British citizens. The most humiliating moment for the Labour Party would come at Corbyn’s hands, as he stood in Parliament and demanded the prime minister explain whether she had complied with Moscow’s ludicrous request to be sent a sample of the Novichok nerve agent used to poison the Skripals, so that, as he later clarified, "they can say categorically one way or the other" whether the Russian state-manufactured nerve agent used in the attempted assassination of a Russian ex-spy belonged to them.
The response from Labour’s own backbenchers to this staggering naiveté was so brutal that the deputy speaker was forced to intervene to ask them to stop shouting at their own leader.