We have a gate the neighbourhood cats climb under as a route through to the stream, and houses behind. They do this in part because both neighbours have dogs as pets.
After some pondering, decided the only thing we have nasty enough to deter cats, that I could sensibly fit to the gate without unduly endangering small children, or their parents, and without making the gate look totally silly, was brambles. So with 6 drawing pins, and some careful pruning of some small brambles I now have prototype cat deterrent number one. I fear it may need bigger brambles, and that will require braving a trip into the wilderness behind our garden fence.
For added effect I’ve also scented the gate with some old aftershave which I usually use as a cleaning solvent.
Better ideas welcome, the gap under the gate is quite narrow, just large enough for small cats to squeeze through. Faye doesn’t want a dog.