My husband and I were at an auction today, and we bid on (and won) this telegraph unit. It came with a paper that says someone named Neal McEwen K5RW did research on it and thinks it's a British GPO key-sounder-galvanometer. All brass key engraved M.W.T. Co. Ltd. 372 1915, sounder engraved G.P.O. 16830, and galvanometer engraved Edison & Swan, No. 18220 1917. They are mounted on a wooden base which slides into a wooden box with a brass handle. There is more information on the piece of paper that came with it about the person Neal tracing the circuitry on the board, and his conclusion that this was made for the British army. I would love to hear from anyone who might have some feel for if this is an unusual or valuable piece, and what it might be worth.