Carrier protection could be distributed through the ship rather than concentrated in a heavily armoured hangar and flight deck. The Illustrious class is the usual starting point for discussions of British armoured-hangar carriers, but Ark Royal already embodied a different protected design. She carried a 4.5-inch belt and 3.5-inch protection over the boiler rooms and magazines, while her flight deck formed part of the hull's strength structure. That arrangement made her an armoured carrier in a broader sense without making her an armoured-hangar carrier of the later standard. Judging the design by flight-deck armour alone understates the protection built into the ship.
Chapter · 4:21-5:12
Ark Royal's protection without an armoured flight deck
Ark Royal distributed protection through her belt, machinery spaces, magazines, and structural flight deck even though she was not an armoured-hangar carrier in the later sense.