Career
Guillaume took up Arabic after studying Theology and Oriental Languages at the University of Oxford. In the First World War he served in France and then in the Arab Bureau in Cairo. Guillaume was a Christian.
He became Professor of Arabic and the Head of the Department of the Near and Middle East in the School of Oriental and African Studies, in the University of London.
He was later Visiting Professor of Arabic at Princeton University, New Jersey. The Arab Academy of Damascus and the Royal Academy of Baghdad honored him by electing him to their number, and the University of Istanbul chose him as their first foreign lecturer on Christian and Islamic theology.