On 10 July 1674 Peterborough was sworn of the privy council, and in 1676 was appointed deputy earl-marshal. In 1680 he was deprived of that office and his pension, and excluded from the council, on suspicion of complicity in the alleged Popish Plot. Nevertheless, though suffering from fever, he had himself carried down to Westminster Hall, to vote against the condemnation of Lord Stafford (7 December) In October 1681 he was summoned to Scotland by the Duke of York, whom he attended on his return to England in the following March. On 28 February 1683 he was restored to his place in the council.