Ok, decided that the best person to ask was my uncle, turns out he has some good info on the car.
Car was first owned by my uncle, then went to another uncle (where all this info has come from) and then onto my cousin, who ended up scrapping it

Firstly some pics :



It was a good shout on the Reiger kit, that's exactly what it is:
From Reiger:

It started life as a 1979 Rabbit Gti and was taken away by Oettinger to prototype his Golf upgrades. Mr Oettinger first did his prototype bits on the Golf and Passat in 1979 (i.e. this golf) He had previously been doing Beetles and camper vans.
I know it is an 81 year reg plate, but original German docs said it was a 79.
Car came back from Oettinger as a 2 litre block, with full Bilstein height adjustable suspension along with strengthened struts and bracing, anti surge sump (which my cousin still has apparently along with some other bits, I have yet to speak to him) and a few other goodies.
The car was first used by Mr VW's son and then brought over to the UK where my uncle got his hands on it.
That's all the info I have managed to get so far
