Maybe it was just me, but back in the 80's in London, we had three or four dogs that freely roamed the streets daily and then went back home. So not strays, there was a tendency for some people to just let their dog do their thing.
Nowadays there would be outrage but back then it felt quite normal.
They would visit other peoples houses, get a snack, everyone knew their names and then they would be off.
There was one dog that visited out house every evening and would play with my dog in the garden. It came over the night before we put our dog to sleep and I never ever saw it again.