Thanks "pkr". I've checked all these fuses and they are OK. Even put a meter across.
I now notice that the heated rear window doesn't work, but apart from that everything seems OK, Internal lights, reversing lights, central locking, heater motor, fan motor etc. As i said, there is power to the windows at the swtiches, so I assumed the problem was some kind of relay opening up the main power through to earth.
I was unaware of the "control box" behind the glove comparment so will investuigatethat tonight.