There were two Greville diarists; they were second cousins:

• Robert Fulke Greville
• Charles Cavendish Fulke Greville (1794–1865). 

Robert

Robert Fulke Greville was the son of Francis Greville, 1st Earl of Warwick and Elizabeth Hamilton. He was born on 3 February 1751 and died on 27 April 1824. on 19 October 1797, he married Louisa Cathcart, daughter of Charles Schaw Cathcart, 9th Lord Cathcart and Jane Hamilton.

His diaries give remarkable insight into the illness and recovery of King George III from porphyria. They also record the King's 1794 season at Weymouth in considerable detail.

• Extracts from RFG's Diaries

F. McNko Bladon (ed) 1930. The Diaries of Colonel The Hon. Robert Fulke Greville, Equerry to His Majesty George III. John Lane The Bodley Head, London.

Charles

Charles Cavendish Fulke Greville (1794-1865) was educated to Eton and Christ Church, Oxford and began his career as private secretary to Earl Bathurst. From 1821 to 1859 he was Clerk to the Privy Council, where he was closely associated with Wellington, Palmerston, and other political leaders of the reigns of George IV, William IV, and Victoria.

• Wilson, Philip Whitwell (ed) 1927. The Greville Diary. 2 vols. London: Heinemann. 
• L. Kronenberger (ed) 1962.The Great World: Portraits and Scenes from Greville's Memoirs.