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Not a bad idea but what you can't fully appreciate is that there's only about 2' of wall above the neighbors gardens where they've been built up over the years, probably with building detritus. Anyway your comment has prompted me to pursue the cranked metal post option a bit further so as to allay my fears of the first gust ripping the fence down and taking the top of the wall with it. It'll hopefully make the other side look like less of a weird bodge too.
A bit like blue physio tape, either side, and bolted all the way through.
I should point out that my old man was a gynaecologist, though, not a mason / hedger, and the chosen solution may have reflected that somewhat.