The more pertinent point is that Murray - a millionaire by the way, not sure how he reconciles that with "for the many and not the few" but there you go - is just one of Corbyn's clique:
John "I am a Marxist" McDonnell, enough said;
Seamus Milne - Privately educated - Winchester College - millionaire Stalinist son of a former DG of the BBC. Surprising that you don't hear more about him given the furore over Cummings and that he's Corbyn's director of strategy and the one who pulls his wires;
Jon Lansman, founder and financier of Momentum, another millionaire who made his money in property. Don't know specifically about his political proclivities beyond being of the hard left and certainly not Liberal.
That's just for starters, sure there's many more.
Didn't know that Johnson's crew include a (or former) Trotskyist; however it's highly unlikely that she'll have the kind of clout that the foregoing have within their wider party.