Today’s object is rather a mystery as despite plenty of digging and asking some very knowledgeable people, I still haven’t got an exact answer as to what it was used for beyond the obvious. Today we are looking at a metal box, painted in a mid-grey colour:
The box has a handle on one edge, indicating it was designed to be carried briefcase style, a small wire latch is fitted above to secure the lid:
The box is hinged along the opposite side, allowing access to the interior:
Note the small compartment in one corner, this has a sliding lid to it:
The box itself is /|\ marked and dated 1943:
I have seen a number of suggestions for the boxes use, with other examples being found marked with a red cross, there is a theory it is a first aid box. Another example owned by a different collector is used for carrying a Primus stove, with the small compartment containing parts. A third example is Air Ministry marked and painted aircraft interior green.
Tales from the Supply Depot 
You don’t give any dimensions for the box.
The maker could well be W.T. French & Son Ltd who were in Ladywood Birmingham (see Graces Guide). Pre war they made a whole range of items so could have turned their hand to almost anything in wartime.
I don’t know about this particular one, given it’s age, but we used similar, pretty much identical, ones for general storage, including some with the same interior compartment.
I don’t remember ever paying attention to when the containers were manufactured but I wouldn’t be surprised if they dated back that far, many other things we used regularly did and probably still do, if something still did it’s intended purpose or another one, we generally hung onto it until it was beyond repair.
The ones I saw were fitted with a thick grey ‘stiff’ foam insert that could be cut to fit pretty much anything you could cram into it.
The foam insert came prescored about every half inch or so on one side and you could break off or partially cut the blocks you needed to until whatever you were fitting in was held snugly or it could be flipped over and cut on the softer ‘plain’ side for an exact form fit or even split into two layers for something with a lot of parts.
The insert was quite a remarkable feat of engineering in itself.
A lot of test equipment came in such containers, very often with very small ancillary parts or spare light bulbs, etc. in the smaller section which was also fitted with a foam insert