Sometimes M1 cameras were used by post offices or similar government agencies for small scale reproduction. It might have been some sort of standard size for a reproduction image they wanted. Or it could have been used in a scientific setting. M1 were used in all sorts different ways. If it has any official markings on it, it may have an increased value. You might post a picture of it on the Photo.net Leica board to see if anyone overthere has more information.