Just been looking up some parts for an owner and thought I would share the findings regarding the thermostatic switch for the radiator.
Part number is H81AB8B607A1A or Finis 6104433. I think that makes it from an Escort, an XR3i maybe.
Ebay had one for sale and advert read... "THIS IS A GENUINE COMMERCIAL IGNITION RADIATOR FAN SWITCH FOR FORDS AND MK1 DISCOVERYS" it then listed some part numbers CI XEFS13 FORD RADIATOR FAN SWITCH 6077895/6077897/6104433/77FB 8B607A3D, XR3I - One of which of course matched what we were looking for.
The picture also makes reference to Lucas SNB710 and Land Rover PRC3366 and VW 251 959 481 amongst other numbers.
Hope this helps,
Justin