Andrew Gabriel wrote:

A fence I installed over 30 years ago using the Metposts is still
fine. They were a make called Fensock which I don't think exists
anymore. They clamp the timber with a pair of nuts and bolts which
close the steal collar tightly around the post bottoms.

I thought they all did that? I've helped the neighbour fit this type,
the thin straps bite into the posts.

https://lawsons.co.uk/product/category/1157/metpost/f25020040