I think it's your punishment for exporting Brit Pop

But seriously, I don't know why there is such a disparity. Are you allowed to shop around for different insurers? Competition in the insurance market is pretty keen here.

Other factors could drive it up, are there tons of lawsuits involving auto accidents in the UK or is autotheft worse?

For example, homeowners insurance here has jumped a good bit from frivolous "toxic mold" lawsuits.