I wanted a single 1 inch 'socket' for my socket set the other day. The only place that sold these locally was halfords (a car & bike shop). Unless I bought a full set I could only buy metric sizes. I ended up with a 27mm socket which did the job (releasing bolts on a line post where the washing line had snapped).
Despite Halfords only selling single sockets in metric sizes, in every case they were marked for use with a 1/2 inch drive shaft!