That might be the case. However, we should not invent new things where old things suffice. Maybe it is as simple as importing digital content, and all that is different in this case is the medium. It's already illegal to import DVDs that contain illegal content into the UK. The person or company that is doing the importing is on the hook. Apply that logic to the the internet medium and we're all set.

As was mentioned in another thread, it is simpler to go after the companies abroad than to build out measures that would prevent such import. Those measures would probably take the form of some sort of firewalls. They would be noticeable to the British people, and the British people, being sensitive about their civil liberties, would not like that. It's easier for Ofcam to go after a couple bigger companies, impose no cost on the British public, and tramp national sovereignty into the ground a bit along the way.