In reply to keith leonard:
Sorry, it was my post, so I appologise for the lack of 'follow up' message.
I believe the dog did get back to it's owner, yes.
As it happens, in Wales it'll be a legal requirement for every dog to be chipped on the 1st March, whether it lives in Wales or is on holiday. That's March 2015!
This dog was chipped, but somehow had no details linked to the chip (the vet was somewhat flummoxed as to how this was even possible...).
As I say, I believe the dog is back where it belongs!