Christian McArdle wrote:
I read the fitting instuctions from the site and they do state boxes
must be mounted 5mm below the wall surface.

Less of a problem with tiled walls, as you don't typically install the boxes
anywhere near the surface of the tiles. If anything, they generally only
protrude from the plaster a couple of mm if at all, leaving a good 10mm or
so to the tile surface.

Christian.

Oops meant to say want to use same sockets throughout and this means on
non tiled surfaces so them the box depth may become an issue?