[3] He was the only son of Sir Allan Horne (died 1944)[4] and Auriol (née Hay-Drummond),[citation needed] niece of the 13th Earl of Kinnoull.
[8] He campaigned against the opening of a Montessori school adjacent to his Turville home because Reverend Paul Nicolson, the vicar responsible for the project, planned to use the project to fund summer vacations at the school for children from nearby London.
[2] He left the world of espionage for history when he was sacked from the Telegraph in 1955, allegedly for offending the wife of the chairman of the newspaper.
[1] Horne was the official biographer of British Prime Minister Harold Macmillan, a work originally published (in two volumes) in 1988.
In October 2006 the book was republished and in January 2007, by phone from his home in England, Horne was invited to take part in an Iraq War discussion panel on the Charlie Rose Show on PBS.
It was reported, in the 2 July 2007 edition of The Washington Post'', that Horne met with President Bush sometime in mid-2007 at the administration's request.