The cats are noticeably less neurotic since I fitted the cat-flap. Hardly a surprise, really: they can come and go as they please, sleep the afternoon away, get up for a light snack, saunter out, take the air, indulge in some elegant exercise, look splendid, out-stare their rivals, kill birds, and come in again and complain bitterly when they get bored of the outside world.
A charmed life, being a cat. Rather like being an 18th century aristocrat, if you think about it. Or a member of the Waffen SS.