Percy Wentworth Hope-Johnstone, de jure 10th Earl of Annandale and Hartfell (2 January 1909 – 5 April 1983) was a de jure British peer and soldier in the British Army.
He was the son of Evelyn Wentworth Hope-Johnstone (9 March 1879 – 26 October 1964) and Eileen Briscoe (died 18 April 1909). He succeeded to his titles as Laird of Clan Johnstone, which included 10th Lord Johnstone and Hereditary Steward of Annandale and Hereditary Keeper of Lochmaben Palace, on the death of his father. He also succeeded to the dormant title of Earl of Annandale and Hartfell, but never claimed it.
He was educated at Sherborne School and the Royal Military College, Sandhurst. After school he joined the British Army and was made a Lieutenant with the 16th/5th Lancers. He was then part of the 155th (Lanarkshire Yeomanry) Field Regiment, Royal Artillery where he obtained the rank of Major. During World War II, he was captured in the Far East during the Malayan Campaign and kept as a prisoner of war.
On 7 July 1932 he married Phyllis Athena MacDonell. They had no children and divorced in 1939.
On 26 July 1940 he married Margaret Jane Hunter-Arundell (8 November 1910 – 5 May 1998). They had two children:
Patrick Andrew Wentworth, 11th Earl of Annandale and Hartfell (born 19 April 1941)
Lady Eileen Elizabeth (born 3 October 1948)