Trotskyists are a “vocal, disruptive and over-bearing” presence within Momentum, whose “sectarian attitude is destructive to our movement,” according to a new member of its central committee.

Laura Murray, who also works as Special Advisor to Labour Shadow Housing Minister Teresa Pearce, attended her first Momentum Committee, since being elected to the post of Women’s Representative, and has written a lengthy and scathing blog post of the divisions within the movement that evolved from the campaign to elect Jeremy Corbyn as Labour leader in 2015.

Ms Murray said Momentum “would be engaging in collective self-denial if we were to downplay [Trotskyism’s] prevalence in Momentum. Dyed-in-the-wool Trotskyists are not the majority in Momentum. But they are a vocal, disruptive and over-bearing minority who have won themselves key position in the regional committees, National Committee and even the Steering Committee.”

Ms Murray said Momentum meetings involve, ‘the loudest and bolshiest person in the room ... proposing pointless motions on policies which Momentum can’t implement, by way of it not being a political party, which are then thrashed out between people who have significant experience in long, boring meetings and take pleasure in angrily arguing for their own narrow and exclusionary political ideology.”

Ms Murray added: “This tendency towards infighting and internal organising is not a luxury which can be afforded to Momentum.”

Ms Murray said the Momentum Committee was completely divided, between younger members allied with its chair Jon Lansman, and older “ultra-left” delegates, whose conduct she described as disgraceful, including “heckling the younger members when they spoke, patronising and mocking them directly to their faces, and leaping up out of her chair to contradict every statement they made”.

The aim of the Trotskyists is to oust Jon Lansman from the group he set up, the “cynical cynical power-plays by individuals more concerned with their own rivalries and egos than with the success of the wider labour movement”.

Ms Murray, who is the daughter of campaigner Andrew Murray, who was chair of Stop The War coalition from 2001 to 2011, said Momentum risks squandering its “generation of young activists – inspired and politicised by Jeremy Corbyn.” She added: “So much for the “new kind of politics.”