The brother of Gerald Lees, Eustace was born in Wolverhampton in 1872. In 1891 he was living at Lower Street, Tettenhall, together with his parents, William and Rosa Mathilda, brothers Lawrence William and Gerald Oscar, sisters Janet R., Mary Eleanor Sophie, Dorothy N. and Constance G., cousin Edith M. L., and four servants – Mary Screen, Martha Allcock, Agnes S. Cartwright and Martha A. Pinney. He was lodging in Colchester in 1901, when he was a Captain in the Army Pay Department. By 1911 he was living back with his parents, in Tettenhall, along with brother Lawrence William, sister Mary Eleanor Sophie, and two servants, Catherine Mary O’Connor and Emily Meredith. Eustace had become a Secretary of the Wolverhampton Eye Hospital.
On the outbreak of war, Eustace rejoined the Royal Berkshire Regiment, and was promoted from Captain to Major. He served in France from 26 July 1915. Eustace survived the war, but does not appear to have married. He died 18 April 1955, when the value of his effects were £3134 13s.