Is there such a things?
I.e. I'm looking for something like this:-
but for fitting into a plaster on brick/breezeblock wall.
... or is the technique simply to fit two metal boxes close next to each other?
Either way with metal boxes the difficulty will be to finish properly between the two.
Would it be permissable to fit a dry-lining box (like the one above) in a plaster/brick wall? It would need a bit of bodging to fix it but would finish properly between the two accessories.
I haven't got enough space really to leave enough gap to avoid disintegration of the plaster between the two boxes.