A colleague of mine had a similar experience with a neighbour of his - he is 50, married with 2 grown up kids - the neighbour would always be looking into his house and if he met him on the street, he would make comments about his wallpaper etc. He put up with this for a wee while until the neighbour gave him a photo of his own house for Christmas and in it, you could clearly see into his daughters bedroom - she was about 20 at the time. He went round to the house and told him what he would do to him if he ever saw him with a camera pointed in his direction again. At the end of the day, he feels that there was no malicious intent involved, just a sad pathetic guy who had no life of his own. You may find that this bloke is just the same. It is difficult to know if there is anything more that you can advise your daughter, as you don't know how this person is likely to react. I think that if it was me, I would be planning a visit to see her soon and go and confront him/see what he is up to. You don't know if he would react unfavourably to them taking his photo/ standing in their own window with binoculars and a notebook. You dont say whereabout in Scotland your daughter is, is it an okay area otherwise, or is it right in the city center?