The duke of Dorset's reappointment to the lord-lieutenancy in 1751, with his son Lord George Sackville as secretary of state for Ireland, strengthened the primate's position and enabled him to triumph over the popular party on the constitutional question as to the right of the Irish House of Commons to dispose of surplus Irish revenue, which the government maintained was the property of the Crown.
In 1808 he was again sent on a mission to Persia, but circumstances prevented him from getting beyond Bushire; on his reappointment in 1810, he was successful indeed in procuring a favourable reception at court, but otherwise his embassy, if the information which he afterwards incorporated in his works on Persia be left out of account, was (through no fault of his) without any substantial result.
He was still but a vali among the rest, holding his many pashaliks nominally by the sultan's will and subject to annual reappointment; and he knew that both his power and his life would be forfeit so soon as the sultan should be strong enough to deprive him of them.
It was to no purpose that he appealed to the emperor and empress for restitution or redress; and it was perhaps the hope of extorting his reappointment to Bobbio, as a reward for his services to the imperial cause, that changed the studious scholar of Reims into the wily secretary of Adalbero.
Only a few months after his reappointment as Augustus's colleague, Marcus Agrippa, his trusted friend since boyhood, died.