After seeing Kate's post I am convinced that a car keyfob is the culprit, as I suspected.
It cant be a neighbour's bell because only I have this gadget round here.
So there is not a lot I can do about it, except learn to ignore it because it is identifiable as the phantom - being like a few 1st notes of one of the 2 chimes.
Just glad to know that I am not being haunted or 'knicknacked' by a hobbit
