We always kept our cat indoors. There were several busy roads near the flat we lived in so it would have been far too dangerous. On top of that, there were (wild) foxes roaming around. Even if nothing had happened, we would always have been worried about where she was and what was happening. We used to live on the top floor of a an apartment building so it would have been hard to get catflaps put on the two doors used to get to the stairs. It would probably have needed the agreement of everyone who lived there. At the best of times, that would have been almost impossible to achieve (some people would be on holiday, some would not like the idea of it at all and so on). Since we lived so far up, there would have been no way to know when she wanted to be let back in. She did not seem to mind being indoors all the time. I think she found it rather comfortable. Actually, there was a cat who lived nearby who looked very similar to her. We think they might have been related somehow: possibly from the same litter originally.