Currently my TR7 Sprint has a manual override switch to control the fan mounted fan. I have bought a thermostatic switch control from a MG specialist on eBay. I thought it would be good to try to do the wiring in the style of how Triumph did it. Cars fitted with air-con had thermostatic controlled fans.
I found this circuit diagram on teamnet http://www.team.net/TR8/tr8cca/wedgelab/other/schematics/schematics.htm
Now need to get some wiring and inline fuse - on order from Vehicle Wiring Products my favorite vehicle wiring specialist.
20/04/2013 The thermocouple sensor part seems to be too long. The top radiator hose has a bend in it near the radiator so the sensor needs to be either flexible or shorter max 30mm I think. Alternatively to get the job done will fit into the bottom hose.