The UK Bloomsbury is just about the only major publisher there that does accept unsolicied mss. I sent one in two years ago (well, first a query, then the full) and they read it in about 6 weeks. The rejection came with a wonderful letter from an editor saying she loved it but they wouldn't know where to fit it on their list. Later, I corresponded with that editor and she tried to help me get an agent - out of the blue, a few weks later I got a mail from a top agent, informing me that the editor had sent him my ms with a recommendation! (He, too finally rejected.)
My dealings with them sent them right to the top of my list of UK publishers. I would die to go with them. However, they are very selctive and have a certainb style they like - tends towards the literary, and preferably a bit quirky, modernistic, dark.
My feeling, though, is that their decisions are less based on aquisition teams and more on editorial input than other big publishers; that editors do not have to take a back seat to the sales and marketing departments when offering on a ms, that they are more independent. I could be wrong but that is my impression.