I've just received my renewal notice from Aviva (c. £800, and high compulsory excess), so I've decided it was time to look around. I've just got 1 windscreen claim in the last 5 years, but the cheapest I could find on a price comparison site was £900, and everyone seems to want a compulsory excess of at least £250.
I tried Lexus Insurance, and they came in at £860 - or £880 if I want to insure against the £250 excess. They might be worth considering for me, if only for the reassurance of having repairs done in a Lexus bodyshop if the worst happens.
It's all very expensive, and my pension doesn't have a London weighting!