Hi Everyone
Thanks so much for the help and advice.
OK to answer some questions...
kevtherev - It is DEFINITELY an Auto Sleeper!
I have sussed the fridge out and got it working on gas. Today I found an additional gas knob in the cupboard below the cooker, which I thought just fed into a spare gas outlet that is on the floor of the van, but I've realised that it also feeds the fridge. Once this was turned on, the gas firing mechanism below the fridge also worked and I can now see a small flame. I left it running for two hours and it's working great.
There are no additional switches on the fridge, and none of the Control Panel switches seem to affect it in anyway, so I guess it just works automatically on hook-up?
I have realised there is a faint 'star' symbol on the switch next to the cigarette lighter socket, which looks like a frost symbol so I guess is related to the fridge. Like I say this doesn't have any bearing on the gas, but do I need to switch this ON to run the fridge whilst driving, but switch it off at the destination to stop it draining the starter battery?
nevill3 - I have not yet been able to test the different scenarios for what the left switch/meter does, so I will test these tomorrow. Thanks so much for posting these.
Finally... yep, the other meter is for the water.
Again, thanks so much.