That is awful news Trish. Some people in this world are just sick! At the end of the day it does not matter where you are now, you have to be careful. Gregors parents friend who breeds golden retrievers lived in the countryside near Kirriemuir (Where I grew up) it is a lovley place very farm orientated and everyone trusts everyone. She had a pup stollen from her own garden when she was in the house! She was so upset by it that she moved a few months later and only had one litter since. That was 3years ago and she is only just starting to get back into breeding again. It is just awful that people can do it.
I think Cairn Terrier is more likely Sophie, I have had a good look through the encyclopedia of the dog and we think it is the most like Sid. Or a Lucas Terrier, it comes under toy dog though not terrier strangly enough so maybe not that. Really cannot see the spanniel but from what you say it is certainly in Sids instinct when you are out!