David Francis Thomas was born in Cork City, Eire, on 5 October, 1913, the son of Frederick Arthur Thomas and Mary Riordan. He was educated first at the Lateran University in Rome and the University of Fribourg in Switzerland, having intended to take Holy Orders. He graduated Bachelor of Philosophy,

Alexander was born in Taradale, Hawkes Bay, and educated at Napier Boys High School and the Otago Medical School, graduating MB ChB in 1939. He was house surgeon at Wellington Hospital in 1940-1941. He served with the New Zealand Army Medical Corps 1942-1945 and was RMO to 8th Brigade in the Pacific