I feel human again.
We have electricity!
After a week of darkness in our lounge and a non-functioning kitchen (which required me to roast our vegetables in an electric frypan in the dining room), Stu identified the problem that has been causing the overload switch to trip out.
He found an electrical box with wires in it buried outside our lounge!
Yes, wonders never cease. After 5 years, we are still learning new things about our house.
The environment in the box was humid and the wires were wet.
Stu moved them around a bit and to lift them up (with the power off, of course!), then left the lid off to allow this week's wind to dry it out as much as possible before we make a more water-proof solution.