Keeble was born in Quetta, British India, and received his early formal education at the Benedictine Douai School (for both prep school at Ditcham Park and the senior school),^[1] and at the Royal Military Academy, Sandhurst.

In February 1964 he received a commission into the British Army's Royal Leicestershire Regiment, which was amalgamated into The Royal Anglian Regiment seven months later.^[2][3] He joined the Parachute Regiment in 1972,^[4] and was promoted to major serving with 10 Para in 1975.^[5][6]

On 28–29 May 1982, at the Battle of Goose Green during the Falklands War, Keeble assumed command of the 2nd Battalion of The Parachute Regiment (2 PARA) after its commanding officer, Lieutenant-Colonel H. Jones, had been killed in action. A devout Christian, Keeble, then a major, took over the leadership of the battalion at a point when its attack upon the Argentine Army position had broken down, having lost 16% of its strength as casualties; it was short of ammunition, had been without sleep for 40 hours, and was in a debilitated condition to face the unknown potential of a counter-attack from the Argentine forces present in the vicinity.^[7] After kneeling alone in prayer amongst the burning gorse seeking guidance as to what to do, Keeble conceived the idea of refraining from more attacks to try a psychological ploy, subsequently releasing several captured Argentine prisoners of war in the direction of their Goose Green garrison, carrying messages into it requiring its surrender or threatening it with a fictitious large-scale assault by the British forces, supported by artillery. The Argentine commander, Lieutenant Colonel Ítalo Piaggi, subsequently surrendered the garrison to the Parachute Regiment without further fighting.^[8]

After the battle, despite popular sentiment among the soldiers of 2 PARA for him to remain in command, he was replaced by Lt. Col. David Chaundler,^[9] who was flown in from the United Kingdom to take command of the battalion. At the end of the conflict Keeble was decorated with the Distinguished Service Order.^[10]

He then commanded 15th Bn Parachute Regiment, a Territorial Army battalion based in Scotland, with its HQ in Glasgow. Keeble finished his military career with the rank of lieutenant colonel on 27 September 1987,^[11] his final appointment having been a staff officer grade 1 at Allied Forces Central Europe in the Netherlands.

After retiring from the British Army he set up a management consultancy, providing instruction on balancing the "Ethic of business transformation with the Ethic of peoples' flourishing". He is a supernumerary fellow at Harris Manchester College, Oxford University.^[12]

• Oak Square Press (2006). 2 Para's Battle for Darwin Hill and Goose Green. Oak Square Press. ISBN 978-0-9660717-1-9.
• Spencer Fitz-Gibbon (April 2006). Not mentioned in despatches: the history and mythology of the Battle of Goose Green. James Clarke & Co. ISBN 978-0-7188-3016-8.