Hi all
A couple of points that might help date the photo. The front forks are of the later pattern introduced during WW1, that style of lightweight fork continued in to the thirties, but there is no anchor for a drum brake, in fact there appears to be no front brake at all! The registration number if genuine, there is no good reason to believe it is not, such as an obvious made up sequence, may provide some sort of clue. Registrations with the letters DD correspond to Gloucester, but from the internet it appears that the 3 letter registrations ADD were not introduced to January 1935, but that is not to say the motorcycle was built then. I would have thought the style of the peoples dress would tend to indicate the twenties rather than later.
Regards SteveL