Oh, and don't go for the cheapest quote. M&S were expensive true, but the policy had everything I wanted, including unlimited buildings and contents and accidental damage. They could not have been more helpful when I had to claim on the contents, to the extent of letting me source a replacement for something when their company couldn't.
Our 1830 house is Grade 2 listed (sounds posh, is actually bit of a pain in the arse) and we got the insurance from a company called Lark Insurance, through the Listed Building Owners society. Normal insurance wasn't going to cover it, as the cost of repair wouldn't be the same as the value of the house - I think the quote's pretty reasonable. Might give you another figure to throw into the bargaining mix?