On Calvert's return to Britain he was appointed Deputy Quartermaster General at the Horseguards, then Deputy Adjutant General 1796. He was made Colonel of the 5th West India Regt and Adjutant General 26 January 1797. At this time Calvert was a rising star, already Deputy Adjutant General, and engaged to a niece of Mr. Greenwood, a partner in Cox, Greenwood, Cox & Co., the army agents. Malicious gossip had it that this connexion was likely to do more for him than any show of martial brilliance, for the
Duke of York was known to have heavy financial obligations to the firm. But Calvert had more than good looks and influence; he stood firmly for the (staff) college. In 1799, having already served as deputy Adjutant-General, Calvert was made
Adjutant-General to the Forces, holding this role until 1818. In this capacity he made improvements in the organization and discipline of the service. He improved the administration of the army medical and hospital department, introduced regimental schools, developed the Junior and Senior departments of the new
Royal Military College, and was largely responsible for the founding of the Duke of York's School,
Chelsea. ==Later life and death==