Thanks all. This has nothing to do with plugs. For the odd bits of UK kit we take over which need plugs atm, we just use an adapter, but most of our plugged-in stuff is French. It's the ceiling lights that seem to be the problem. And it's nothing to do with saving a few € on the cost of the lights, as I've spent £1500! When we got the diagnostics they pointed out the old and new wiring which was still wired up to an ancient fusebox. EDF came out and replaced the fusebox and everything bar the old sockets seem to work. It would appear, tho, that the wiring for the lights is still the old stuff. I'll get an electrician over next time we're out and they can have a poke around and make sure we're not going to burn down!