In Another Job for Biggles Doctor Guthram Darnley was a noted traveller and explorer who crossed the Rub al Khali in a camel caravan and discovered a source of the resinous narcotic drug gurra in shrubs growing in the Wadi al Arwat. Darnley collected some seeds which were cultivated in Kew Gardens. The plants soon died but botanists at Kew were able to identify and classify the species. Later when gurra turned up mysteriously in spiked cigarettes in London, Biggles was sent to destroy the only known source of the drug at the Wadi al Arwat. Darnley supplied Air Commodore Raymond with the names of the three Arabs from Aden who had accompanied him on the expedition, Abu bin Hamud, Kuatim and Zahar. As the only other people on the expedition with any connection with the outside world, it was believed that they must have some connection with how gurra had made it out of the wadi. Darnley does not appear in the book in person. The account of his discovery of the wadi and the gurra plants was related to Biggles through the Air Commodore.