Allan was born in Brisbane on 16th May, 1914, the fifth son of Charles Constantine and (Mary) Edith Warren. He was educated at Rudds College, later renamed Brisbane Boys College and completed his secondary education at the Geelong Grammar School, Victoria. He was in England when the war broke out in 1939. He entered an officers' training unit in October 1939 and was a Lieutenant in the Royal Northumberland Fusiliers by April 1940. In June 1943 he transferred to Special Operations Executive ( "Force 133" ), promoted Temporary Captain and after a parachute training course was described by his Chief Instructor as "an ideal commando type", tough, with plenty of common sense, and also with a pleasant personality. On 11th August 1941 Captain Warren was parachuted into Greece, where he served as a member of the Allied Military Mission’s unit in Thessaly, under Lt. Col. Sheppard. Early in 1944 the Mission began to plan "Operation Conjugal", in which a number of Russian and Polish escaped prisoners of war were to be evacuated in a Greek motor-caique from the port of Galaxidi, on the northern coast of the Gulf of Corinth, to Italy, which country; had been largely reoccupied by the Allies. Captain Warren was placed in charge of the operation, which was to begin on 20th March. The embarkation took place as planned, and the caique got to within 60 miles of the Italian coast when disaster overtook it. It ran out of petrol within sight of Italy and then it encountered a heavy storm which blew the helpless vessel back to Greece. On the 25th March, off Cape Mounda, near the port of Skala in the south-east of the island of Cephalonia, it was intercepted by a German patrol-boat. Two days later a German radio broadcast news of the capture. A fortnight afterward a signal from Major Ramseyer of one of the Allied Military Mission stations in Greece confirmed that Captain Warren and all but one of his party had been taken prisoner, including an American air force officer, 15 Russians, 3 Poles and the Greek crew of three. The one man who got away was a Russian, who escaped by swimming ashore under fire. He made his way eventually to the Greek mainland and reported to Major Ramseyer. Captain’s Warren’s fate thereafter has never been clearly ascertained. According to one report, by a Russian ex-prisoner of war to a British officer in Thessaloniki in June 1944, Captain Warren and his companions were taken to Thessaloniki and there held in a prison camp. During his internment Captain Warren tried to escape by digging a tunnel under the wall of his cell, but was detected. According to the same Russian prisoner, Captain Warren was taken from his cell one evening at about eleven o’clock – the usual time when prisoners destined for execution were removed. He did not take his kit with him, and was never seen again in the camp. The Russian supposed that Captain Warren had been shot. Another report quotes a Greek guerrilla officer as saying that Captain Warren was not taken to a prisoner of war camp, but to No. 510 Gestapo Prison in Thessaloniki, and that he was executed there between 15th and 20th May, 1944. Whether the German authorities regarded him as a spy, or whether they killed him as a reprisal for trying to escape, may never be known. Whatever the truth, his death is a grim reminder of the hazards faced by the Allied officers and men who served in Occupied Greece.
