I dont think this was the SWP but part of the same mentality. During the time of Troops Out (probably before some posters were born) there was an effort to recruit 3 respectable young women (and seemed to think they would be found in Women's Liberation groups).
The were to take part in a demonstration which would disrupt the Trooping of the Colour. Some young impressionable feminists felt they owed a duty to help demonstrate against english colonial occupation of Northern Ireland, but they were persuaded not to volunteer just because of the danger of dashing in among the horses (ie intended as politics of spectacle - ie good front page images for the papers).
Years later if was revealed that in fact Troops Out had been infiltrated by an undercover cop who became quite senior in the organisation.
There was much speculation as to whether the attempt to recruit women to do this, was in fact a black ops gambit, with the intention that had the women been hurt it would have a negative impact on Troops Out.
Not saying that the SWP would ever go that far (just dillitante posh boys), but for instance engineering a situation that leads to kettling, is one way of getting a response to police being heavy handed.
Similar of course to the tactics used at the Sarah Evarard Memorial event which had been peaceful and respectful in line with family and organisers wishes for most of the day, ie no political chants or leafleting. That is until a small group, supported by the SWP, arrived in the evening with load hailers and political banners, encouraging those attending to converge onto a smaller and smaller space. The police acted to stop some sort of crush which including asking those with loud hailers to "move along". Which they didn't do, so were then open to being arrested leading to the very useful picture of a woman being "man handled" by the police.
And hey presto, next day all the headline were about the police and the then new public order bill, and nothing about Sarah Everard.
Unfortunately there is always a steady stream of patsy, whether by name or nature who get caught up in this manipulation of the situation.