Duetto Electrics

I have been having issues with the 12 volt transfer when I disconnect from mains - sometimes the 12 volt system works at others it doesn't - any clues where to start looking for the problem please?

It would be a good idea to say roughly how old your Duetto is, as the model has been made for many years, and there can be big differences between different years.

Sorry if it's obvious to you and/or doesn't match your symptoms, but presumably you're aware that the internal 12V system is (on most models) intentionally disabled when the ignition is on or the engine is running?

Engine and ignition off thanks - its 1998 if that helps

Sounds like the leisure relay.
I'm not sure where this is on a Duetto, but probably near the battery.
There should be 2 or 3 relays which are obviously not part of the original Ford, but fitted afterwards by Autosleepers.
Try pulling each of these out of its socket, give it a gentle tap, and push it back in again.

Thanks - found it in a separate box - just dangling on 5 wires - got a replacement from local Ford dealer (fitter had an old second hand one in a tin of bits!) - hope that has solved the problem, certainly seems to have done so far