It was created on 19 May 2018 by Queen Elizabeth II as a subsidiary title for her grandson Prince Harry, Duke of Sussex, upon the occasion of his marriage to Meghan Markle.

[3] It is named after the small fishing port of Kilkeel, County Down, with a population of 6,887, in the District of Newry, Mourne and Down in Northern Ireland.

[4] Traditionally, male members of the royal family are granted at least one title on their wedding day by the monarch.

[5] Prior to 2018, there had never been a noble title connected to Kilkeel (from Irish Cill Chaoil, meaning 'church of the narrow'[6][7]), which lies within the historic barony of Mourne.

[8] In the Middle Ages, it was said to be the centre of power of the Mugdorna (Múrna, Mughdorna, Mourne), an Irish tribe.