Gibb was born on Wednesday, 2 January 1895, in
Alexandria, Egypt, to Alexander Crawford Gibb, the son of John Gibb of Gladstone, Renfrewshire, Scotland, and Jane Ann Gardner of
Greenock, Scotland. His father died in 1897, following which his mother took up a teaching position in Alexandria. Hamilton returned to Scotland for his formal education at the age of five: first, four years of private tuition, after which he started at the
Royal High School, Edinburgh in 1904, staying until 1912. His education was focused on
classics, though it included French, German, and
physical sciences. In 1912, Hamilton matriculated at
University of Edinburgh, joining the new honours program in
Semitic languages (
Hebrew,
Arabic, and
Aramaic). Hamilton's mother died in 1913 while he was studying in his second year at university. He had two brothers, Euston Gibb and Archibald Gibb.(family knowledge) ==Military service==