So what are the relative merits of https://www.screwfix.com/c/electrical-lighting/back-boxes/cat7230011#category=cat2470003 vs https://www.screwfix.com/c/electrical-lighting/back-boxes/cat7230011#category=cat830524 ?
I have 2 surface mounted electrical sockets on the existing wall. I want those to be sitting flush when I've finished. I understand that I need to remove them, cut holes for the new recessed back plates, fit the plasterboard and Bob's my uncle. But what I can't work out is how I work out exactly...