1939;
12 4" AA (6x2)
24 2pdr AA (3x8)
36 aircraft 

Originally designated as a light battlecruiser but first completed as a makeshift aircraft carrier, Furious was rebuilt with a lower hanger at the level of the previous forecastle deck and an upper hangar and flight deck above. A short flying-off deck was built over the bows, and the upper hanger opened up to this. There was no island until a small one was fitted during her 1939 refit and the boiler uptakes were led aft to discharge either side of the round down or lower hangar; this was an unsatisfactory arrangement and one not repeated in British fleet carriers as it led to problems with escaping heat and also meant that insufficient workshop space was available, so that part of the lower hangar ha to be used which meant a reduced numbers of aircraft could be carried. The short flight deck was disused before 1939 and the main flight deck, which was 91½in wide, had a usable length of 530ft, increased to 596 ft in 1943. The hangars measured 550ft lower, 52 ft upper x 50ft x 15ft; the two cruciform lifts were 46ft x 47ft, the forward one taking 12.500lb and the after 14.000lb and both serving either hangar. Petrol stowage, at 20.800gal, was limited. The flight deck was 1in steel and the total of other deck protection 2in max. The original bulges had been increased to improve stability but the system was only designed to stand 440lb TNT.

Modifications: In 1939 Furious was completely rearmed with 12-4in. QF Mk 16 HA in twin mountings, and the 8-barrelled pompoms were increased to three. A fourth was added in April 1941 and subsequently 15-20mm Oerlikons were also added. In spite of her unsatisfactory features she gave good service during the war, and emerged virtually unscathed. In 1942 her bulges were deepened to improve stability, which increased extreme deep load displacement to 28.495 tonnes and GM from 2.5 to 4.9ft.