I know, which is why I am stumped. My only deduction is that the problem is with the connection of the switch feed to the loop. So I will need to trace this back to where it links in.
I now have a bit more info. Loop is definitely in ceiling/loft. There is absolutely no power to the switch. There is a scary looking junction box (no cover) in the loft which seems to have more connections than it is designed to take, and as such it is difficult to see what goes where, but there...
"Is access to the circuit easy? Does the loop run in the ceiling, or through the switches?"
The bulk of the wiring is in the loft, with drops into a false ceiling for the extra low voltage transformers/lamps. The switch cables are sunk into the plaster. Not sure how any of this relates to...
Firstly thanks for the speedy responses.
Secondly - They were on a dimmer - but in an attempt to discount a switch problem, this has been replaced with normal switch, yet the lights will still not come on.
6 low voltage (12v) downlighters with dedicated transformers (i.e. 1 per light), sold together, i.e. as a single unit (suggesting transformer is correct rating for light).
The 6 low voltage lights in my bathroom all 'went out' simultaneously. They were NOT switched off, but simply 'went out' as I was bathing. Circuit breaker is not tripped, and bulbs are not blown. This is the second time this has happened since the bathroom was recently refitted. The first time...