Well, I’ve fixed it myself!!! I traced it back to a dodgy stalk. So I’ve disconnected all of that and left the stalk there just for looks.
I’ve wired in new brake lights powered to the master cylinder the back to the lights. Being USA spec it has all red rear lights. So I’ve put in two flasher units one for each side to a 3 pin toggle switch and ran those wires to the reverse lights so now I have amber indicators and I have a retro little chrome light that I’ve put on the bumper to act as a reverse light. None of the original wiring has been cut or moved so I can easily put it back to standard if I feel like it.
Feeling pretty chuffed with myself as I’m rubbish at electrics!