In message , F
writes

The lights may have stayed on but did everything else? Their lighting
may be on one circuit, 'theirs', but the expensive stuff might be on
another, 'yours'.

Good point. I'll ask, tomorrow. We have a whole maze of fuses, boxes
and on/off switches here, including a huge grey thing that looks like it
should control Battersea power station.
--
Graeme