After initial service in the fleet Torrens-Spence volunteered for flying duties with the Fleet Air Arm, which at that time was under the command of the Royal Air Force. After flying training, he was commissioned as a pilot in both the RAF and the Navy. His first postings were on the carriers and, in 1937,.
When war broke out, Torrens-Spence was serving on Glorious which was sent through the Suez Canal to hunt German surface raiders. He was then sent home from Aden to join the new carrier. Whilst serving on Illustrious, which had been dispatched to the Mediterraneanin September 1940, he took part in the attack on Italian battleships in the Battle of Taranto as a Swordfishtorpedo bomber pilot. During the Swordfish attack in Taranto harbour, he torpedoed one of Italy's newest and largest battleships, the, sinking her in shallow water. He was awarded the Distinguished Service Cross for this action. He was also involved when Illustrious was badly damaged; Illustrious was escorting a convoy to Malta when she was attacked by three squadrons of German Stukadive bombers. Suffering multiple bomb hits and more than 200 casualties, Illustrious limped to Malta and eventually to America for repairs. Her aircraft were disembarked in Malta, and Torrens-Spence flew to Eleusis, near Athens, Greece, with elements of 815 and 819 Squadrons for an active anti-shipping campaign which later earned him the Distinguished Service Order. At the Battle of Cape Matapan, Torrens-Spence was ordered to find and attack a large Italian naval force. After observing an attack by aircraft from the carrier achieve no result, he found a hole in the enemy smokescreen and was confronted with the, which he torpedoed from close range. The cruiser immediately slowed to six knots and the Italian admiral decided to divide his force, leaving a large detachment to escort Pola and sail for home. That night, the Royal Navy engaged with the Italian force off Cape Matapan, and with the aid of radar sank the major part of them. Polas captain was rescued by the destroyer and was heard to remark, "Either that pilot was mad or he is the bravest man in the world". Admiral Andrew Cunningham wrote in his dispatch after the battle: "An example of the spirit of these young officers is the case of Lieutenant F.M.A. Torrens-Spence who rather than be left out, flew with the only available aircraft from Eleusis to Maleme... arranged his own reconnaissance and finally took off with a second aircraft in company and took part in the dawn attack." From March to October 1941, Torrens-Spence commanded 815 Squadron in Albania, where he added to his tally. Unfortunately, this included a hospital ship which the Italians had failed to mark and illuminate. No blame was ever attached to Torrens-Spence, but he was forever saddened by the incident. From 1942, Torrens-Spence was posted to the UK to become a test pilot at Boscombe Down where he remained for the next three years, until posted back to Illustrious for the closing stages of the war.
After leaving the Royal Navy Torrens-Spence was appointed as the Commandant of the Ulster Special Constabulary in County Armagh. When the Specials were disbanded in 1970 and replaced by the Ulster Defence Regiment, Torrens-Spence took control of the County Armagh Battalion, as a lieutenant colonel, to get it up and running. He retired in 1972.