CPGB-ML are mostly pretty solid - we work with them a lot of the time, and they have a principled position against the Labour Party and British Imperialism. The other ones tend to be pretty negligible -3/4 people only turning up for May Day marches and so on.
Hey comrade! Yeah the RCG is an ML organisation -we're politically quite similar to the PSL in the USA, and have a similar history too.