He was a firm believer in the reality of the Popish Plot, and in concert with Ralph Montagu, whom he helped to get into Parliament, took an important part in the attack on the Earl of Danby.
The revelation of Danby's secret dealings with France elated him to the point of hysteria: one historian has described his Commons speech on the subject ("poisoning and stabbing are in use....I am afraid that the King will be murdered") as "ravings".
In the parliament of 1679, in which he represented Thetford, he spoke against Danby's pardon, attacked John Maitland, 1st Duke of Lauderdale, and was eager for the disbanding of the army.
He accompanied William of Orange on his invasion of England in 1688, and the following year was made a Privy Counsellor, to the dismay of the Tory party, and Paymaster of the Forces in Ireland.
He left England on 9 November, arriving in Vienna on 8 March 1692 to mediate between Sultan Ahmed II and the Emperor Leopold I, but died in Belgrade of a malignant fever, before reaching his posting in Constantinople, on 31 July 1692.