The Duchess of Hamilton of 1908 was Nina, née Poore. Her article in thepeerage is here. Her eldest son became the 14th Duke of Hamilton and he gained some notoriety when Nazi Deputy Führer Rudolf Hess attempted to reach him by aircraft in 1941 to broker a peace deal. Douglas ratted on Hess so Hess got to visit the Tower; Douglas was a double agent for MI5. Hess was sent to Nuremberg to stand trial at war's end. Hess died in Spandau prison and his remains were ultimately cremated and the ashes scattered at sea.
The photographer is stated to be Speight. This could be Charles Speight, but there were other UK photographers named Speight.