During the First World War, he was commissioned into the Gloucestershire Yeomanry and rose to the rank of captain.
[4] [5] Within a few months of inheriting the estate, Guise sold much of it, while keeping Elmore Court and a home farm, and also Lassington Wood, which he soon gave to Gloucester County Borough Council, to celebrate the Guise family's long association with the city.
[3] Guise also inherited an art collection, and in 1921 he sold Francesco Botticini‘s painting “Madonna Adoring the Christ Child”, which had belonged to his mother's family, the Coopes.
[6] In 1922 Guise was commissioned as a Justice of the Peace for Gloucestershire, and in 1926 was “pricked” (appointed) as High Sheriff of the county.
[2] Their daughter Philippa married Alastair Hugh Joseph Fraser, of Moniack Castle, the eldest son of Major Alastair Fraser and Lady Sibyl Grimston.