In Biggles Works Overtime, Sheikh Ibn Usfa was the sheikh of a small sheikhdom on the Arabian Red Sea Coast south of Jiddah (today, Jeddah) known as El Bishra. About three years before the events narrated in the story, Eustace Bowden was an R.A.F. pilot in a flying-boat squadron stationed at Suakin on the African coast near El Bishra. Bowden had a forced landing on the Arabian side and then spent two weeks as a guest of the sheikh while waiting for a relief plane. Later, Bowden brought the sheikh ovr to be a guest of honour at one of his squadron's guest night.
Three years later, Bowden flew out to the region in an Aircom Owlet with a companion, Anthony Renford. Ostensibly on an attempt to break the solo light plane record from London to Cape Town, Biggles discovered that Bowden diverted to El Bishra, landing in the night. He then made his way into the palace, being welcomed by the guards who knew him from his previous stay. He then murdered the sheikh and made off with his valuable pearl collection.
The sheikh did not appear personally in the story. When Biggles came out to El Bishra to investigate the activities of Eustace Bowden, he was received by the Sheikh's son who told Biggles what had happened to his father.