The Gloster Gladiator biplane fighter was the last and best biplane of the British Air Force. Biplane design was already considered outdated by the time production of the Gladiator started, but it was clear that Britain might not have time to develop mass monoplane production before full-scale war began. The Gladiator was released as a modification of the Gauntlet, replacing the obsolete Bulldog biplane fighter. The wing and landing gear were redesigned, the cockpit covered, and landing pads added. At the request of the Air Force, the armament was increased to four 7.7 mm machine guns. The Mk.II model had the more reliable Bristol Mercury VIIIA / AS engine with an output of 830 horsepower in place of the Bristol Mercury IX (which had the same horsepower).
A total of 717 Gladiator aircraft were produced, 311 of which were the modified Gladiator Mk.II.