Hi Ron, i have the same box as on your picture. Maybe there might be a connection to the RAF as mine came together with a wooden toolbox of a civilian fitter mechanic ho was working on the RAF base in Wevelgem just after the war.
Yes I think they are a tool box Guy. As I say, I have one stamped 'Air Ministry' as well as a WD version. Ideal to carry a reasonable amount of tools from workshop to vehicle/air-plane.