Why is that cat flaps have to make a disconcerting flap-flapping noise upon opening and closing. It seems to frighten the life out of young Bella and Arthur. Segregating one of them off temporarily into the cat basket I showed them in turn the workings of the cat flap, and then walked them round from the front to the back garden and over the fence. They seem to prefer using the (human operated) patio doors… 😉