Riley is a collie owned by Squadron Leader Rex. Following Rex's appointment to Hornet Squadron, Riley becomes the squadron mascot.
A veteran flyer, who usually travels with Rex, Riley has clocked up to 300 hours in the air by the start of the war, although he tends to get distraught when flying above 4,000 ft. He also has a habit of emptying his bladder on anyone below the Rank of Squadron Leader.
Following Rex's death in combat, 'Fanny' Barton is forced to stop Riley's howling by shooting him in the back of the head.