I think once coinlab in US starts running then UK will follow, coinlab is actually going to have insurance for holdings via Lloyds of london, so the city boys know all about it.
I would have thought that coinlab got insurance on Lloyds of London because that is just about the only place in the world that would consider providing a high sum assured contract covering Bitcoins.
I also think the UK is suffering due to the hurdle you have to get over just to get involved in Bitcoin. If you can't get bitcoin quickly and easily, it limits the number of people getting involved. Then you get a chicken and egg situation - a well-backed UK exchange that could meet the regulatory burden would probably be successful. But without one, there are not enough UK users to justify setting one up.
I think one way to get people involved, is to make something attractive. In the context of an exchange, one attractive element is liquidity/participation. The way to create that, is to initially have a prop trader churning over volume. How much cost/risk is implied here, is probably above my pay grade, but i for one, would be very happy to sit and churn required volume all bloody day!