Denis Sidney Sanders was an aircraft engineer but showed a wide and detailed interest in windmills, watermills and mill work in the 1930s - 1970s. Sanders was born on the 16th September 1917 near Worthing, Sussex, and married Doris L. Young on the 31st October 1941. From October 1942 he was an active member of the SPAS (Windmill Section) and became a member of the Newcomen Society in December 1948 and at meetings he took an active part in discussions on windmills. He was a frequent contributor to the discussions of Wailes's windmill papers to the society but published very little himself. He created 164 careful measured detailed field notebooks, which run from 22 August 1943 to 24 November 1973. Sanders died on the 4th March 1974 at the age of 56.