Greville was returned for Monmouth as a Tory in 1747 by his kinsman, the 4th Duke of Beaufort, but did not stand again. In 1756 he published what Horace Walpole (to Conway, 16 Apr. 1756) referred to as
a wonderful book by a more wonderful author, Greville. It is called Maxims and Characters; several of the former are pretty: all the latter so absurd, that one in particular, which at the beginning you take for the character of a man, turns out to be the character of a post-chaise.
Later he was described by Fanny Burney as
the finest gentleman about town ... His high birth ... with a splendid fortune, wholly unfettered, already in his hands, gave to him a consequence in the circles of modish dissipation.1Mems. of Dr. Burney, i. 24.
The date of his death has not been ascertained, but he was living in February 1805 with a fortune much depleted by gambling.2Farington Diary, iii. 60.