 Just Henry entered the service of the Landgrave in Sweden as Writer to Major General Ernst Hartmann von Diemar, with whom he moved to London in 1725 as Registrar.Henry successively became Secretary, Private Secretary, Counsellor, Minister, and, 1760, Privy Counsellor, until his death in 1768.In later life he assumed the title "Baron of Hesse-Kassel," though its provenance is unclear as the title "Baron" was never awarded by the German Emperor.