He became an activist with the Bertrand Russell Peace Foundation and the Popular Front for the Liberation of Oman, working with the Omani opposition at the United Nations in New York City.
Glubb reported from Beirut during the Lebanese Civil War, first for CBS and later for the Daily Mail as Michael O'Sullivan.
He published several books, notably Zionism: Is It Racist?, The Palestine Question and International Law and Zionist Relations with Nazism.
When he died, he was working for a doctorate in Arabic at the School of Oriental and African Studies about relationships between Richard the Lionheart and Saladin from Vatican documents.
He was survived by his second wife, Salwa and their two daughters Sarah and Darina, and his son Mark (Mubarak) by his first marriage.