[1] He was educated at King Edward VI School, Birmingham, and then at Clare College, Cambridge, from where he earned a first class honours degree in natural sciences.
Hadley inherited a library of fishing books from his father which he rebound and he was a fly-fisher himself as well as having an interest in oriental rugs.
Being of a professional standard in cello and with instruments provided by the Red Cross, he helped establish an orchestra in his prisoner of war camp.
[1] Having plenty of time on his hands, he was also closely involved in the prisoners' observations of nesting birds, the studies of which found their way into the Collins New Naturalist book series after the war.
[3] His war-time experience greatly affected him, however, and he turned from a pre-war "typical medical student – outgoing with a love of fast cars"[3] to an "intensely shy and often monosyllabic" man who developed a "reputation for epigrammatic description"[1] from which he partly recovered with the help of his wife.