Carns was born and raised in Aberdeen, Scotland.[1]
Military service
Carns joined the Royal Marines in the other ranks.[1] He was commissioned as an officer on 4 September 2002, and appointed to the trained strength on 29 September 2003.[2] He was promoted to major on 1 October 2010,[3] to lieutenant colonel on 30 June 2016,[4] and to colonel on 26 July 2021.[5] He left the Royal Marines after 24 years of service in May 2024 to stand for election to the House of Commons.[6][7]