I took in a feral cat 7 years ago and I have never been able to train her to use the cat flap, my other two cats took to it no problem. So since I've had her I've had the flap stringed up so that it's permanently open - even over the winter when I freeze!! The problem now is that one of my other cats, a 17 year old, shouldn't really be going out anymore as she forgets where to come back to and sits in the middle of a road the other side of my house. I now need to stop the older cat from getting out but letting my other two, including the feral one, have full access. Are there such things as automatic / mechanical / pneumatic cat flaps where the flap will automatically open - if I can get the feral to wear a collar!! Or does anyone have any ideas on training a feral cat to use a cat flap? Thanks, Ben.