In Biggles in Borneo, Talut Island was a small island in the Sulu archipelago, a chain of islands stretching from the Philippines to Borneo. When Algy and Ginger were returning from a reconnaissance of Cotabato, they discovered a poisonous krait in their cockpit and decided that the only safe course was to bale out. They landed on Talut Island where they were taken prisoner by a party of Japanese soldiers who were stationed there in a submarine refueling base.
Biggles later went to Talut Island using the Cayman, bringing Suba, Kalut and Captain Rex Larrymore in order to find out what had happened to Algy and Ginger. They found the wreckage of Algy and Ginger's aircraft but they were nowhere to be seen. Suba and Kalut were sent to kidnap a Japanese soldier from the base and by questioning the prisoner, Biggles was able to determine that Algy and Ginger had been taken to Cotabato on board a submarine.
No such place as Talut Island exists but there are many islands in the Sulu group which could have served as analogies for it.