This is a wonderful period shoot from 1935. The bike is an Ok Supreme, and can be an Brittania from 1933/34. I am not sure, there are something that are different from the sales catalogue. Can be an Phantom with foot change?
The bike was sold off before the war, and we don`t know if it still exist.
The Britannia was the top of the line from Ok Supreme. The other models had hand change and deeper mudguards. The Britannia was listed with secial cylinder head, foot change Burman 4 speed close ratio gear box, Webb TT girder fork and could be delivered with BTH racing magneto.