Yes, they are honeybees - DBH is a bit of an expert on insects, but even he doesn't want them in our bedroom and upstairs bathroom, which was where they were when we investigated. So they are coming down through the loft floor, where the holes are cut for the recessed downlighting. I went upstairs while DBH looked up the local beekeeping association, we will ring tomorrow. What we have done for now is put a piece of sellotaped cardboard over every single downlight we can reach - all ten of them, only one we really can't get to. We shall be living in the light of bedside lights and shaving mirror only until the problem is solved. I can see me forgetting about the ones on the landing though.
When we moved here there was a big empty space between our room and DS's, which went over the hallway, we worked out. So DBH decided to knock it through and make us each a big storage cupboard. When he did, he discovered that no, the buzzing noise I had been complaining of really hadn't been in my imagination. The wasp's nest was almost as big as he was. We still have some of it as a souvenir - and the smaller but complete one next to it!
Until we realised that we had a problem, I was just gaily letting bees out of the windows and remarking to DBH that we had an awful lot more of them in the house than usual. When I went upstairs after I wrote my first post on the matter, there were dozens on the carpet, none moving, but a couple of dozen more behind the blind on the window sill, still alive. If there had been only one or two I think we would have just slept with the windows open and the blinds up.