After retiring Kemp co-wrote Attack State Red with Chris Hughes, an account of the 2007 Afghanistan campaign undertaken by the Royal Anglian Regiment, documenting their initial deployment.

Having trained as an infantry soldier in 1977 at Bassingbourn Barracks, Cambridgeshire, he attended the Royal Military Academy Sandhurst and was commissioned as second lieutenant on the General List on 5 August 1978.

[citation needed] He then took over the Armoured Infantry Training and Advisory Team based at Hohne and Sennelager, and held a staff appointment in the Ministry of Defence.

[15] The title of the book comes from the British military standing operating procedures (SOPs) for the alert state of a base referring to the likelihood of attack.

[16][17] Kemp told the Belfast News Letter that he was concerned about the investigations into historic crimes, stating "It is obvious some soldiers do some wrong things of course but there is a very clear difference between them and terrorists.

[23] Kemp was involved in the "Honour the Brave" campaign led by the Daily Mirror in 2007 and 2008 to recognise the sacrifice of British troops killed or wounded in action by the award of a medal similar to the US Purple Heart.

Kemp featured alongside others who have spoken out against Islamist terrorism on a video released by the Al Qaeda group al-Shabaab, which was responsible for an attack on a Nairobi shopping mall in 2013.

The video included a clip from the BBC TV programme HARDtalk of Kemp condemning the murder of Fusilier Drummer Lee Rigby in Woolwich.

"[29] The article was condemned for stigmatising all young Muslims as "potential terrorists" and undermining attempts to increase diversity in the British armed forces.

[31] On 11 March 2015 Kemp visited the University of Sydney to deliver a lecture on "Ethical Dilemmas of Military Tactics" and the complexities in dealing with violent non-state actors such as ISIL.

This lecture was interrupted by a group of pro-Palestinian demonstrators led by Associate-Professor Jake Lynch, the director of the university's Centre for Peace and Conflict Studies.

[32][33] In April 2017, a column written by Kemp and published in the Jewish News suggested that Baroness Warsi had sought to excuse the conduct of the Islamic State group.

"[34] On 23 July 2018, The Daily Telegraph published an article by Kemp which argued that after its departure from the European Union, Britain should re-instate the death penalty for terrorism suspects.

[38] Kemp was appointed Member of the Order of the British Empire (MBE), Military Division, on 25 April 1994 in recognition of his intelligence work in Northern Ireland in 1993,[39] and was awarded the Queen's Commendation for Bravery for service as a commander in the United Nations Protection Force in Bosnia in 1994.