Sir John Riddell, 13th Baronet

Sir John Charles Buchanan Riddell, 13th Baronet, KCVO FRSA (3 January 1934 – 24 July 2010) was Private Secretary to the Prince of Wales from 1985 to 1990. He was Lord Lieutenant of Northumberland from 2000 to 2009.

Riddell was born at Hepple, Northumberland. He succeeded to the Baronetcy of Riddell of Riddell as an infant, on the death of his father in 1934. The family seat at Whitefield House, Hepple was bought by his ancestor Sir John Buchanan Riddell (1796–1822) from the Duke of Portland in 1804.

Riddell was educated at Eton College and Christ Church, Oxford, and served briefly as a Second Lieutenant in the King's Royal Rifle Corps (1952–54) before qualifying as a chartered accountant.

In 1969 he married Sarah, daughter of Baron Richardson of Duntisbourne, who bore him three sons between 1974 and 1982.

Riddell worked with the International Bank for Reconstruction and Development in Washington from 1969 to 1971. He was associate director of First Boston Corp from 1972 to 1975, and director of First Boston (Europe) Ltd from 1975 to 1978. From 1978 to 1985 he was director of CS First Boston, to which he returned as deputy chairman from 1990 to 1995.