Ok - I have four cats who I love to bits and yes - cats can be a real problem for others which I do appreciate. My reply to this, whilst trying not to be biased in any way is this: we live amongst farmland and have two occasional cat visitors and I've never found where they come from. You can get certain cats who leave their owner (if they had one in the first place) to spend their lives wandering from place to place being fed by all and sundry. I agree that neutering here is the right way to go (if you can find then catch them in the first place). Territorial invasions or mating competitions can sometimes result in the awful noises you hear and also injury to the unsuccessful one, and I'm afraid there is little you can do about it as that is the way they live, but see the next bit as to legislation for roaming cats. Currently, it seems that they are regarded as "semi-wild animals," and I believe they are difficult to train accordingly because they are not pack animals with one master that will follow his or her orders - i.e. - unfortunately they are a law unto themselves. To find any animal wee and poo in your garden and/or trashed plants isn't nice at all, have experienced it with my cats, could be a health hazard and I really sympathize here with you. All I can say is that any pet owner should take as much care as they can, not just for their pet's welfare, but to try whatever they can to prevent it from causing problems to their neighbours. I'm lucky in that my nearest neighbour is about three big fields away, but if I lived in a different area, would personally do everything I could to minimise it or help in any way I could, and hope I had neighbours that would appreciate my efforts.