Well my mistrust and general contempt goes back to the Freedom to Party movement in '89... Lots of people busted, beaten and jailed for throwing parties.
A few thousand people at Trafalgar Square protesting about it all, slagging off The Scum "newspaper" and generally demanding the right to do what the fuck we want if it hurts nobody... And sure enough the SWP were there trying to claim credit for it.
Didn't last long though, some Swappie twunt managed to grab the microphone and start banging on about lesbian equality and oppression of the working classes, she was shouted down and laughed off the stage within seconds by the hordes of muntered punters, and replaced by a flute player doing a rendition of Guru Josh accompanied by a human beatbox.
Only then did people realise the event had been potentially hijacked by a load of beret wearing Marxists (or cunts, as Ricky Gervais accurately observed) and the SWP members were abused and ejected accordingly. I think the girl who got laughed off the stage cried.
It was a good day for people who like to organise a bit of a protest without the interference of a load of self serving tossers trying to canvas support for their blurred agendas.