 From 1897 to at least 1899, Sydney and his wife Maude were active in the early modern feminist movement, promoting practical clothing for women through organisations such as the Western Rational Dress Movement and Cycling for Women.His reputation as an over-zealous splitter seems to have been justified.As one example, a 1966 analysis of his observations on "Sonninia" (a genus of ammonite in family Sonniniidae) reduced 70 species down to two.