No nothing to do with Darwin or genetics but I am missing the coupling that fits on the end of the gear linkage to join it to the selector on the gearbox. I did purchase a Mini one ( at about £20) thinking I could modify it to fit but no luck as you have one 13mm hole at 90 degrees to the other and the Mini one is a simply a tube 50mm long.
For my next attempt I tried using a solid tube of aluminium and bore the two 13mm holes. Did manage to make one, however due to inaccuracies from having only a vice and a battery drill, when fitted nothing would move! Is some clearance on all joints of the linkage required to help it operate? Any suggestions?
I am beginning to wish I bought a complete car and not a heap of assorted parts.

I would get in touch with Derek Hambly. He should be able to sell you one

https://hamblysportscars.jimdo.com/

Simon

I have them if Derek can't supply.

Thanks rossabitz. Let me know how much and I ll buy one from you.

A big thanks to rossabitz for supplying the coupling, great service.
With much fiddling, swearing and torn knuckles I have a smooth working linkage, at least on a static engine .
A few points to bear in mind to anyone setting up a linkage from scratch.
First the engine should be parallel to the linkage. I achieved this by first pulling the top of the engine backwards towards the rear of car and fixing the top steady at this position. In addition the ends of the moving linkage ( U shaped rod ) required a little adjustment in the vice with a hammer. I also removed the bobbins on the bracket holding gear selector to tunnel.
Second with the gear lever removed the moving ' cup ' in the selector should be in the centre of the selector housing when gearbox is in neutral. I had to adjust the length of the fixed rod with the lock nuts to achieve this. This position seems vital to give enough travel in any direction to obtain all gears.
Finally don't over tighten nuts on linkage as some play helps it to operate.
Well that's one job sorted, hope this is useful to someone.