We're thinking about having our gas meter moved from the lounge to the outside wall of the house. There is a pavement right outside, and I'm reluctant to go with a surface mounted box (plus they're *really* ugly). As such I think we'll opt for a cavity box. However, the house was built in 1850 ish and so has stone walls that are about 570mm thick(slate slabs really). Is it ok to put a cavity box in a wall like this (which I suspect doesn't really have any sort of cavity)?
Cheers for any help