I thought I was being slightly ironic. 
However, to be pedantic, 1 inch = 25.4mm. A 16mmm box is about 3mm deeper than an old half-inch box and those few mm make a hell of a lot of difference when you try and fit a modern, slightly deeper switch where an old, very shallow switch used to be. I wonder how many people have done just that and ended up with some very squashed insulation behind?
I particulary pity all those who have gone out and bought those flat plate chromed accessories and then tried to get them to fit flush against the old patched plaster finish of their 1920's terrace.
However, to be pedantic, 1 inch = 25.4mm. A 16mmm box is about 3mm deeper than an old half-inch box and those few mm make a hell of a lot of difference when you try and fit a modern, slightly deeper switch where an old, very shallow switch used to be. I wonder how many people have done just that and ended up with some very squashed insulation behind?I particulary pity all those who have gone out and bought those flat plate chromed accessories and then tried to get them to fit flush against the old patched plaster finish of their 1920's terrace.
