Not sure - someone here said they thought something had happened in Brighton but I can find no mention of anything on the Net. As Val said earlier, in these situations there are always "chinese whispers".
I have just heard Brighton too and also Swindon. Everything is shut in London now and Police have told everyone not to leave their buildings. Luckily we have a cafe downstairs so we won't starve!!
We've been told to stay here and not even leave our buildings - not sure what's happening yet. Been called in as emergency powers as a Special Constable but can't get there so that's not much use