could you imagine a dystopian future where the left leads the fight against pamphleteering?

that wouldn't be a left at all - that would be an authoritarian right. no left worth calling itself such would support any legal action against pamphleteering whatsoever.

i'm not being alarmist, or perhaps i'm being proactively alarmist; i understand that the police need to investigate a complaint, and i'm not suggesting they shouldn't be doing so.

but, the police should be coming back to the mosque with some stern words about freedom of expression - and a clear explanation that this type of behaviour is constitutionally protected in this country.