He served in the Northumberland Hussars and the Royal Regiment of Artillery during World War II, rising to the rank of captain.

[2] When his father acceded to the dukedom upon the death of his paternal grandfather, the 7th Duke, in 1918, he became known as Lord Hugh Percy.

[3] He became 10th Duke of Northumberland on 21 May 1940 when his childless elder brother was killed in action in Flanders, Belgium, in the leadup to the Battle of Dunkirk.

[7] He also took on management of the family estates, namely Alnwick Castle in Northumberland, Albury Park in Surrey and Syon House in London.

[11] In 1957, he gained the additional peerage of Baron Percy upon the death of his kinsman, James, 9th Duke of Atholl.

[18][19] On 12 June 1946, he married Lady Elizabeth Diana Montagu Douglas Scott, daughter of the 8th Duke of Buccleuch, at Westminster Abbey.

[6] The marriage united the Percy and Douglas families who had feuded for centuries, including at the Battle of Otterburn in 1388.

[6][21] They had seven children: The Duke died of a heart attack at his London home, Syon House, on 11 October 1988 at the age of 74.