Occam's razor
Exactly, Occam's Razor - a useful concept, if occasionally (as in your case) misunderstood.
oh dont be sillier than you have to be.
Indeed, though that is wishful thinking on so many levels ;-)
My friend (you've heard of him, as have most Poles; I don't always agree with him, though he is sensible) suggested it may be Russian provocateurs. Though I doubt that. And for sure it isn't a Brit: nothing points to that.
A bigger worry is not cultural centres but ordinary families targeted by nationalistic thugs. At least we can be sure that the UK police will come down on that like a ton of bricks
(I've seen British Council on Jerozolimskie Av.
In what way is that a community centre? Btw, it closed a while ago.