Away from the drama of the Tory leadership election, Labour’s internal troubles rumble on. Yesterday’s PLP meeting was described as Jeremy Corbyn’s “worst meeting in his time as leader”. That’s really saying something, given the years of tension between the Labour leader and the majority of his MPs.

The sources of the trouble weren’t new. Apparently the absence of a defined (and fully pro-EU) Brexit policy, and the ever-present, unaddressed issue of antisemitism formed a twin focus for the argument. On the former topic, several MPs reportedly said they had found it hard to vote Labour in the recent EU elections. On the latter issue, yesterday saw insult added to injury when Corbyn and 30 other Labour MPs turned out to applaud the new MP for Peterborough, despite troubling revelations about her past actions.

But this is hardly the first time Remainy Labour MPs have been unhappy, or that a resurgence in antisemitism in and around the left have turned people’s stomachs. If anything, these are familiar features of Corbyn’s leadership, reliable constants in a turbulent world.

Rather, the newsworthy element is the suggestion that these concerns are being voiced by MPs who were previously loyal to the leader, and therefore largely silent about inconvenient and uncomfortable problems. To an extent that’s a sign of these issues becoming bigger and bigger problems, but it’s also an indication that Corbyn’s personal authority, once absolute, is wearing at least a little thinner. Not only are Shadow Cabinet members like Emily Thornberry testing to see how far they can push the boundaries, but so it seems are some backbenchers.

Why is that erosion of authority and growth in open dissent happening now?

Gaby Hinsliff undoubtedly has a point when she says that the prospect of a new Conservative leader, and a possible election, is sharpening minds on the Labour benches. I suspect there’s also – on the EU issue at least – a growing feeling that the party membership is no longer as completely or automatically in line with Corbyn’s policies as it once was. The mass membership elevated him to leadership, defended him against all challengers, and was long seen as a stick with which to beat troublesome MPs – who are now gingerly testing whether that is still the case or not.

That’s not to say that we’re about to see an actual revolt against the Labour leader. These MPs have spent years swallowing unpalatable things about him and those who come with him. By definition, those in the PLP right now have opted, regardless of their dislike of or supposed concern about what he says, thinks, or does, to carry on backing him to be Prime Minister. There’s little reason for them to change tack now, given what they have already waded through.

Indeed, if these experiments at testing the strength of his authority succeed, and the PLP finds it can actually force Corbyn into some policy changes, then they might become even more accommodating of his many downsides. Their most desired switch appears to be on Brexit policy – if he granted it to them, how many Labour MPs would quietly bury their discomfort about anti-semitism (and security, and the economy, and foreign policy…) for a bit longer?