Really appreciate it, thanks! Kids have gone to their grandparents. I was guessing I'd need to switch off the supply outside, so that it'll be tomorrow now!
Thanks again.
I turned off the internal mains stopcock earlier today so that I could fix a broken tap. Now when I turn it back on there is no supply. I briefly turned it back on and the off whilst I was doing the fix, in order to flush the loo and see whether the tap was ok. The supply came on and switched...