Hi all,
I have just read this thread and I have to say it is not normal for the cooling fans to run whilst the car is being driven, there should be enough airflow through the rad to cool the system properly. It would indicate to me that there is another problem if this in fact the case.
In the normal scheme of things on the Saff the cooling fans would run on for a short time after the ignition is turned off.
The Kenlowe type capillary action t/stat with a bulb on the end that sit underneath the radiator hoses are notoriously hard to seal properly. and really have no place on a high performance car. I wouldnt risk trashing my Cossie motor with a sudden leak from one of these!
If your existing fan circuit is dodgy then far better have a switch on the dash and keep an eye on the temp gauge.

CheeRS, Mike.