Thorneloe is the highest-ranking British Army officer to have been killed in action since Lieutenant Colonel H. Jones's death[1] in 1982 during the Falklands War.

[8] He served in Northern Ireland as a platoon commander and company second-in-command, and also worked for a year as an intelligence liaison officer for his regiment, liaising with the Royal Ulster Constabulary Special Branch in South Armagh.

[14] He was appointed battalion adjutant[2] and, on 30 September 1999, was promoted to major,[15] and posted to Permanent Joint Headquarters, Northwood, where he worked in intelligence analysis.

[9] The Times said that the divisional commander Lieutenant General John Cooper "looked on Thorneloe as his right-hand man in analysing and presenting the options in this process".

[2] Thorneloe was promoted to lieutenant colonel on 30 June 2008,[17] and became Commanding Officer of his battalion just before it deployed to Afghanistan in April 2009 with about a Battle Group of about 1,000 troops based first at Camp Bastion and later in Nad-e-Ali in Helmand Province.

[2] Thorneloe was killed by the Taliban in Operation Panther's Claw while riding in an 18-vehicle convoy when an improvised explosive device exploded under his BvS 10 Viking armoured vehicle.

[21] Thorneloe's death reinvigorated debate over the adequacy of military equipment supplied to British forces in Afghanistan, with charges focusing on the alleged lack of transport helicopters, which forces troops to travel by land and become exposed to Taliban IED attacks, and the inadequate protection offered by Viking armoured vehicles against IEDs and land mines.

The service was attended by Charles, Prince of Wales, Camilla, Duchess of Cornwall, Des Browne, and Thorneloe's family.