They should simply be promptly reminded that Sharia law is not in effect here & arrested if they harass the general public/try to enforce anything (like anybody else would if they did the same for any other reason).
I do think we should get a basic constitution, enshrining basic rights (nothing stupid like the US one) but within in equal rights for all groups - which would pretty much make any form of islamic religious law illegal in the UK (due to its homophobic and sexist nature).
If anything it might shut up the mass paranoid delusions of some members of the UK public who think Islamic culture is going to take over in the next few years.
On a side note, I always find moral preaching hilarious from religious institutions with questionable moral guidelines.
Half of them sound like a bunch of Yob's to me, looking for an excuse to get shirty with random.
