A very long time I covered the emergency pattern map case here. That design was an economy case to replace the standard No2 map case, and it is this version of the map case we are looking at today:

This case was approved and added to the list of changes in August 1940. The case is made up of three main pieces. At the back is a tufnol board, a pressed composite board made of resin impregnated cloth, that the map is rested upon:

To this board is rivetted the canvas top cover, which passes over the whole map case and secures with two brass Newey snaps. Between the tufnol board and the cover is a celluloid sheet that protects the map and allows chinagraph pencils to be used:

Swivelling brass tabs are used to hold the celuloid down and keep the map in place:

The underside of the top flap has a set of sewn in loops:

These allow a square protractor and four pencils to be carried securely:

The underside of the flap has the manufacturer’s stamp:

W & G are the initials of Waring and Gillow. This company were orignally a furniture manufacturer, but during the Second World War they diversified into webbing manufacture.
I have no proof of this, but I have seen far more of the emergency pattern map case when compared to this, the earlier standard pattern. If this is the truth, I don’t know but the change over to the emergency pattern seems to have come early in the war and this, the earlier pattern is less easy to find on the collector’s market.