Thank you for your advice Zuleme. I looked at your archives and enjoyed more of your gorgeous cat photos as well as finding the bit about the fence. I'll see if something like that is available in France. The main problem is that our back door opens onto a bank with a wall they can easily jump on and holes they can get through to the neighbours. Then there's the problem of two upright sleepers - one on our side and one over the fence. Needless to say a favourite game is to leap from one to the other. But I'm working on it.