Thanks for the advice everyone. He went to the guitar guitar shop in birmingham and got a martin d-13e road series. 2 and a half times over budget but he is now as happy as a pig in sh
Have you tried doing a rubbing of the logo impression on the headstock? bit of white paper over it, rub lightly with a pencil or crayon - might give a clearer view of it.
Time-wsie, my best guess would be 50s-early sixties, European - possibly German?