This week the Labour campaigning group Momentum produced another of its very effective social media videos promoting and defending the interests of Jeremy Corbyn. This one was an attempt to argue that Mr Corbyn had been the victim of “demonisation” and it included clips of a number of people criticising the Labour leader.

Most were fairly routine accusations or well known (Cameron advising him to do up his tie) but one of them I found quite striking. Footage of an interview with Chuka Umunna was included in which the Independent Group MP was asked whether, in his view, Mr Corbyn was a Marxist. “I think so, yes,” he replied.

Now, we can debate whether this is an accurate description of the Labour leader. I think