.Is that a bolt hole through the leg that you can ..err..put a bolt
through ,or is it intended for something else .??

Bolt hole is in the centre of rotation if the leg does work loose in
the bracket.

It's a serious question, not a criticism - I'd looked at the axminster
ones before as my traditional timber-jointed ones are getting a bit old
- but I had doubts their ability to remain stiff when getting pushed
around a bit.

I'd figured making wooden trestles (like builders steel trestles - but
not a disaster if I run a circular saw into it one day) - less portable
but will happily take heavy timbers etc.