Information has come to hand that leads me to believe that Netta was the daughter of Alfred Woods Hanckel, although not yet proven.
From the India Office List 1933:-
HANCKEL, Alfred Woods, A.M.I.C.E., M.Sc., late Indian Service of Engrs. -- Apptd. tempy. engr., Bombay, 3rd Jan., 1903; asst. engr., Jan., 1908; exec. engr., Feb., 1912; serving under Nepal Durbar, Oct., 1917, to July, 1918; retd., Jan., 1927.
In the 1901 census Alfred was an unmarried engineer so it seems from about 1903 he was in India until about 1927 when he retired. It's not known if he returned to the UK or not but as Netta's photo turned up there he probably did, if indeed Netta is his daughter.