Followed stocktake's diagram, I now have a working cooling fan! The 3 speed hadn't worked since I bought the car but it was never an issue until the recent hot weather when I really wished I had AC.
Appreciate all the advice given! If only I'd thought to check the relay box before I chopped my connectors off the diesel box...
had to do a bit of additional soldering to make good but all sorted now.
The shorter fan shroud/cowling gave me false hope that it had come off a diesel which was clearly not the case.
Thanks all!