He became major in 1787, visited England in 1789, and purchased a lieutenant-colonelcy in 1790, returning to India in the following year.
Promotion followed in 1749 to a majority, and in 1750 to the lieutenant-colonelcy of the loth, with which he served in Scotland.
Mr Roosevelt declined the colonelcy of the regiment, preferring to take the post of lieutenant-colonel under his intimate friend Dr Leonard Wood, who, while a surgeon in the United States army, had served in action with gallantry and skill against the Indians.
He was given the colonelcy of the 10th (Lancashire Fusiliers), but was too late to take part in the battle of Culloden.
In 1747-1748 he was again with the duke of Cumberland in the Low Countries, and in 1749 was transferred to the cavalry, receiving the colonelcy of the 7th (3rd) Irish Horse (Carabineers).
He entered the army as ensign in the 73rd Highlanders in 1787, passed rapidly through the lower ranks (in five different regiments), became major of the 33rd (now duke of Wellington's West Riding), and purchased the lieutenant-colonelcy of that regiment in 1793 with money advanced to him by his eldest brother: But in all these changes he did little regimental duty, for he was aide-de-camp to the lord-lieutenant of Ireland for practically the whole of these years.
The few and miserable triumphs of Sweden during the Seven Years' War were due almost entirely to young Sprengtporten, and he emerged from it with a lieutenant-colonelcy, a pension of X20, and the reputation of being the smartest officer in the service.
In 1770 Granby, worn out by political and financial trouble, resigned all his offices, except the colonelcy of the Blues.
In 1636 he entered parliament as member for Stafford, and during the Civil War held a colonelcy in the parliamentary army.