The SWP are Trotskyist, in the sense of "March through the institutions". If you're doing anything left wing they will turn up and try to make it about them, take over organization positions, etc. The SWP are mostly your boring old lefty uncle, with a side of institutional rape apologia: https://www.gender-agenda.org.uk/not-my-comrades-on-dealing-... (this is not only their problem, it can happen in any organization that doesn't take active steps to avoid it)
I suppose the canary for partisan moderation should be Sinn Fein; they were banned from television in the 90s.