Ordered from Armstrong Whitworth at Elswick in 1914 as a "light battlecruiser" fitted with two 18in guns and laid down on 8th June 1915. She was launched for completion in that design on 15th August 1916.
On 26th June 1916 it was decided to convert the ship for use as an aircraft carrier. In 1921 she was taken in hand for a third change in design. Work was carried out by HM Dockyards at Rosyth and Devonport and provided a full length flight deck with Bridge structure and funnels removed. In addition there was a small lower flight deck forward. This was dispensed with after aircraft weight and speed increased. Exhaust gasses were discharged by uptakes led to the stern. The bridge facility was replaced by an open type at the deck edge. The ship joined the Fleet in 1925. Further changes were made to the stern structure and the quarterdeck was raised to flight deck level between 1931 and 1932. The ship was modernised and refitted before the outbreak of WW2 and she re-entered service with six twin 4” mountings controlled by two gunnery directors for AA defence.
Displacement as an aircraft carrier was 22,450 tons with an overall length of 786 feet 3 ins., a beam of 89 feet 9 ins. over bilges and a draught of 25 feet at full load. The main propulsion was provided by steam turbines of 90,000 SHP driving four shafts to give speed of 30knots. Armour was provided for protection of machinery and steering gear with external bulges for underwater protection. Armament provided included the six twin 4in mountings and three eight barrelled 2 Pdr Pom-Pom mountings. During WW2 this was increased by single 20mm Oerlikon mountings to improve defence against close range air attacks. The radar fit was minimal, compared with other Fleet aircraft carriers and was fitted during wartime refits as was required to suit deployments. Total complement including aircrew exceeded 1200. By the end of WW2 about 30 aircraft could be carried, depending on type embarked.
This ship was extensively deployed during WW2 until withdrawn from operational use when modern Fleet Carriers became available supplemented by several Light Fleet and Escort Carriers. She took part in operations off Norway throughout the war, carried out deliveries of aircraft to Malta and to the Middle East via West Africa as well as providing air cover for Atlantic and Malta convoys and supporting the allied landings in North Africa.
After the end of hostilities in Europe she was placed in Reserve and sold for breaking-up in 1948.