Mrs Blue Tit sitting on the top of the bird box - she seemed to be worried by a couple of Wood Pigeons that were pottering around beneath her.
By this morning there were three eggs, but she doesn't seem to have been sitting on them much - she did have Andrew the electrician fairly close by, putting up a new outside light, but even after he had gone she didn't return and we still haven't seen any food being delivered to her when she is sitting on the eggs. Do hope they're going to be alright !