English, c.1915, marked to the top plate 'M.W.T.(Marconi Wireless Telegraph) Co Ltd, LONDON No738', case opens to reveal a set of handwritten instructions to the underside of the lid along with a hand-drawn circuit diagram, and an ivorine plaque for attaching notes, top vulcanite plate with air capacitor and other control knobs, with mount at the back for the two valves (both OSRAM P2) with a set of military DLR headphones, all in a green canvas covered mahogany case, case 30cm wide