 Gayre was born as George Robert Gair on 6 August 1907 in Dublin to Robert William Gair (1875-1957), a confectioner, and Clara Hull or Hart, and in bogus pedigrees recorded in Ireland in 1950 and published between 1952 and 2003, he claimed that his father was the son of William Gillies Gair (1842-1906), a portrait painter born at Greenock in Scotland, but was actually the illegitimate son of the painter's sister Jessie Gair (died 1897) who, two years after the child's birth became the second wife of William Sutherland, of Glasgow, plasterer.He earned an MA from University of Edinburgh, then studied at Exeter College, Oxford.Gayre served with the British Expeditionary Force in France in 1939, as a Lieutenant-Colonel in the Royal Artillery afterwards becoming Educational Adviser to the Allied Military Government of Italy, based in Palermo, where he fought for the exclusion of left-wing text-books and communist influence from the Italian education system.