He continued to maintain the family's substantial electoral interests, and to collect objets d'art to decorate Belvoir Castle.

He acted only as an observer until reaching his majority, and made his maiden speech on 5 April 1775, advocating free trade with the southern American Colonies.

During the American Revolution, he followed Chatham in urging reconciliation with America, and was one of those who questioned the conduct of Admiral Keppel in March 1779.

While the Irish opposition was later reconciled to Pitt's bona fides with regard to trade, the episode demoralized Thomas Orde, the Chief Secretary of Ireland, and further hindered efforts at reform.

In the summer of 1787, he made an extended and rigorous tour of the midlands and north of Ireland, but his excessive consumption of claret was by now taking a toll upon his health.