What a joy this has been. Ref Kane's comment below. This may be the S &D based post mentioned. Standard gallows post with a bar along the top - twist and lift.
On t'other side of the region on SER metals, the same game. The Ratio design is a bit of a puzzle with flat linkage and the bump bar fastened at the ends so that the ends lift and open upward rather than the usual 11 and 1 o'clock as above. I can find no SR pictures to match it.
My take was to use the post and bar and wire supplied - make up three holders from strip (handrail knobs might be nice here) and use two of the supplied links for the outriggers. The cable is the thinnest wire I could find stripped out of layout cable. A closer view at the flickr link below at Heathfield (plus a lot of other very nice shots). It's too low, but after swearing and cursing for most of yesterday I gave up with it for a while. The parts are so fragile and you are fighting the spring of the wire all the time.
The more I work though this project the more I am drawn back to the easy world of the freelance modeller where you can pick and choose your pieces. Here there are rules, you have to stick to them and do hours of detailed research. This is tricky stuff, the freelancing is a piece of cake in comparison.