Yes. Thanks for the link.
I am now working (slowly...) on some idéas on how to do what I want.
Right now my idea is this. The car originally had a heated windscreen. This is no longer the case. The windscreen has been changed.
But the switch for turning it on and off is still there: I hope to be able to use that switch, and the relay that belongs to it, to override the radiator thermal switch.
But to be able to do that, I have to locate that heated windscreen relay first. That requires a removal of the dashboard. That is now the next step.
I hope I can keep the forum informed of my progress here.