Oh if only that were possible Jon! Cat flaps one could programme! We don't much like SmokeyPokey going out for too long as he's sixteen and quite frail, although seems perky enough. One fight with that Horror over the road would be the end we reckon. But it seems a shame both our cats can't come and go as they wish. We daren't go out shopping ourselves unless our two are safely indoors and the cat flap locked shut.
It has to be said, much as we all love our cats, at times they're a Blooming Nuisance!!

By the way, I broke my heart yesterday. I was sitting on the famous bench out the front when I saw the Horror's housemate Marmite running home with a poor fluttering female blackbird in his mouth. I rushed over to our neighbour, who has the nest in her woodshed and has fed the blackbirds all winter. She was in tears. The Thing had torn down the nest; there were three smashed eggs on the ground. And no doubt the female bird would be tortured until it died. We comforted each other and had a cup of tea together. What can one do? My husband was furious and sad when I told him.