Thanks, everyone. Have had a chat with the kids (I put it in our joint names two years ago) and the consensus is to pay the Planning Gain fee, sell it, and buy a student flat down here to rent out. We reckon the neighbours won't bother anyone else, as all the planning issues were ironed out and the conditions to the approval clarify that. If I developed it myself they'd maybe try to cause problems. They are all nice people really, my architect says it's just because I'm not one of 'them' any more. It's sad but there it is - life.