One phonecall to the insurance company later and my OH is now main driver on the policy. Spoke to three people who all sounded suprised when I mentioned the quote difference, and could offer no explanation.
Can't think how I am higher risk; I've been driving 13 years, him 3. I've never had an accident, he had an at fault accident 1 year ago. I'm 31, he's 30. Oh well. It's maybe better this way as he does drive more often than I do. It was nice being able to drive oter cars though!