I would think that a more than significant number do not.....they are too expensive to just sit on the deck as a bit of boaty bling, You will probably see more of them if you frequent the posher boaty areas, and Marinas.....but there are thousands of boats up and down the UK, that are not kept in Marinas, in fact I would venture to suggest, that there are more boats in the cheaper end of the price range where a life raft is not seen as top of the list when it comes to parting with ones hard earned.....From a safety point of view, people who are sailing on a tight budget, make different arrangements for their safety.