I think ICTS are employed for more than just US flights at DUB; I was flying to JER last week and ICTS people were doing random checks on hand baggage. Very courteous, I have to say, in fairness.
As for LGW, I've never seen anything about photography been banned airside. I've always taken photos there and except on one occasion, when I was told that taking a photo of a Monarch 757 was not allowed due to FAA regulations (yes, you read that right), I've never been stopped.
I'm considering a letter to the leader of the Parliemantary Transport Committee; it is a pretty toothless group, but I think it is useful for enthusiasts to have a place to put our views forward. The point needs to be got across that airport authorities have a choice: they can try to make photography and an interest in aviation as difficult as possible and divert resources best employed in handling the real threat to aviation, OR they can accept that they will never discourage enthusiasts and instead, view them and deal with them as assets in the fight against terrorism. Their choice, but that choice needs to be made public.
I'll let you know how I get on.