Update: I just went to the door to have another look at the cat and the next door neighbours head poked over the fence, having heard the meowing.
Lucky I wasn't caught in the act of unending a bucket of water

Apparently it's a new addition to their cat household, and is a rescue cat. Very friendly for a rescue! Anyway, came over the fence and then apparently got confused about where to go next, so was asking us for help in it's own way.
If it happens in the future, at least I know which fence to turf it over.

"Human beings, who are almost unique in having the ability to learn from the experience of others, are also remarkable for their apparent disinclination to do so." - Douglas Adams
I
Nomes &
Gibbo