On Jul 20, 11:44*am, Luke wrote:
cutout 366mm W * 532mm H * 160mm D

Measure your wall thickness & cavity with a drill.
Depending on house age if it needs 160mm from the outer leaf front
face, you may find you would have to partly core-drill and breakout
part of the inner leaf too (easier to use block and cut them thinner).
If you do try to stick a lintel in the outer leaf, you would need to
use stainless flat bar or angle which is too expensive unless
salvaged.

You can get flush floor mounted gas meters, they use a different
compact meter type.