 He corresponded with Charles Darwin who lived at Downe, some 30 miles from Thames Ditton, and Darwin drew heavily on Watson's unique appreciation of the distribution of British plant species.In 1856, Watson actually declined a personal invitation to discuss evolutionary theory with Darwin and Joseph Hooker, because he was too busy and did not wish to travel.Nevertheless, in "On the Origin of Species", Charles Darwin made generous acknowledgement of Watson as a vitally important source of scientific information and, in turn, on the publication of "On the Origin of Species", Watson was one of the first to write to Darwin – on 21 November 1859 – congratulating him on his extraordinary achievement.