The younger son of the Earl of Portsmouth, he briefly sat in Parliament on a family interest and later died in captivity in France during the Napoleonic Wars.
John King, who had ambitions to enter Parliament, wrote Pitt in 1800 to say that Wallop was "little better than an idiot" and "has spent all his money," so that his mother was willing to put up another candidate for Andover if a pension of £400 a year could be obtained for him.
Pitt declined, and Wallop sat in Parliament until the next election, in 1802, when he was replaced by his elder brother Newton.
[1] While there, he was alleged to have carried on an affair with the wife of another English detainee, which prompted the French authorities to remove him to the fortress of Bitche in February 1805.
He was returned to Verdun in May 1806, but his health had suffered badly, and he died suddenly of apoplexy on 31 August 1807.