No no, no nastyness, I am more curious than anything else as to who it is, I mean, if they were casing our house out then they would have burgled us long before now.... unless its an opportunist thief of course.
The thing about it is that despite it being a shortcut, it is only really to the back gardens as we are at the end of a row of houses. I have never heard of any problems, and whoever it is doesn't do any damage or leave much evidence if anything, so, I'm not sure if its a thief or someone who lives in one of the other houses taking a swift detour