Parents who think that the library is their own private creche. Don't get me wrong. I'm all in favour of children being exposed to books and the joy of reading. So long as they're at an age where they are reasonably well behaved and, more importantly, not shouting at the top of their lungs or trying to run an indoor marathon around the bookshelves, then by all means absolutely bring them in. But seriously, bringing babies and very young toddlers into a library and expecting them to be quiet is just plain daft, not too mention extremely inconsiderate towards other users of the service. I won't smoke in their creche if they don't scream in my library.