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thanks to everyone who cares, I am going to knock on a few doors and explain to the owner, he is outside again now. The first time I knew they were an "item" was when I came home one afternoon opened the front door and this cat was coming down the stairs followed by VEB with tail in the air, they took one look at me and carried on slowly down the stairs walked passed me into the kitchen and out the cat flap, no panic no picking up the pace just as though it was their daily routine !
I will get another cat after a while, not a kitten but an older female cat whose owner has probably died and needs to be loved again.