They were constructed one each in England, Scotland and Northern Ireland to the same basic design during the Second World War for service with the Royal Navy.

One of the class, Campania, was the first British carrier to be fitted with an Action Information Organisation (AIO) and a Type 277 radar able to detect low-level aircraft.

Once completed the first carrier did not take part in active service until January 1944, but all three served as convoy escorts during the final year of the war.

[2] Following the successful conversion and operation of HMS Activity, the Admiralty decided to take over three more merchant ships while they were still under construction and convert them into escort carriers.

[3] The three ships chosen were being built at three different shipyards around the United Kingdom, Harland and Wolff in Northern Ireland, Swan Hunter in England and John Brown & Company in Scotland.

[6] They had the same propulsion provided by diesel engines connected to two shafts giving 11,000 brake horsepower (BHP), which could propel the ship at 17 knots (31 km/h; 20 mph).

Both carriers left the River Clyde on 29 January with the 2nd Escort Group under the command of Captain Frederic John Walker.

They were to form a "hunter killer group" in the waters west of Ireland, providing cover for two southbound convoys OS 66 and KMS 70.

The U-boat U-592 was sunk by Wild Goose and Walker's own ship Starling, while a Fairey Swordfish from Nairana circled the area.

[13] Leaving Northern Ireland on 9 March 1944, 2nd Escort Group moved to the area believed to hold the highest concentration of U-boats.

[15] Weather conditions were still not perfect for flying and in the following days, one Swordfish returning from a night patrol landed in the sea alongside the carrier, the crew were reported missing believed killed.

Landing on the heaving deck was just as dangerous, two Sea Hurricanes and two Swordfish missed the arrestor wires and ended up crashing into the safety barriers.

[17] With Vindex damaged and needing a refit and Campania still not commissioned, Nairana was the only ship of her class fit for sea on 1 April 1944.

[18] She still had 825 Naval Air Squadron on board but this time she was overloaded with 18 aircraft: 12 Swordfish Mk IIs and six Sea Hurricanes IIcs.

[22] Russian convoy JW 61 which sailed on 20 October had for the first time three escort carriers, Vindex, Nairana and HMS Tracker.

[24] Vindex's inexperienced squadron lost a Wildcat pilot when his plane crashed into the sea attempting to land back on board.

[25] Campania was commissioned in February 1944, her delay in construction meant she was the first British carrier to be fitted with Action Information Organisation (AIO) and a Type 277 Radar able to detect low-level aircraft.

She had 813 Naval Air Squadron on board, equipped with 12 Swordfish Mk III, four Grumman Wildcats and three Fairey Fulmars.

Both journeys were relatively uneventful no U-boats interfered with their progress and the only action was the shooting down of two Blohm and Voss 138s by the Wildcats of 813 Naval Air Squadron.

[25] The normal Arctic convoys restarted at the end of November, Campania and Nairana were paired as part of the escort.

[25] On 6 February 1945, Campania, Nairana, the cruiser HMS Bellona and eight fleet destroyers joined 26 merchant ships in convoy JW64.

[27] The long Arctic night with only four hours of light a day together with heavy seas and low visibility hampered any operations by the Wildcats.

Campania's night fighting Fulmar took off at 17:30, but its electrics failed as it was approaching the German aircraft and it was forced to return to the carrier.

[28] The combined losses had reduced the escorts fighter cover three aircraft, one on Campania and two on Nairana at 11:30 another group of Junkers Ju 88 torpedo bombers were discovered approaching.

[29] The return convoy RA 64 left Kola Inlet on the morning of 17 February, one of the escorts and a merchant ship were torpedoed almost immediately.

Terrible weather conditions kept all aircraft grounded until 20 November, when it began to clear the Luftwaffe also appeared and the Wildcats were scrambled to intercept them.

[31] Campania did one more Russian convoy JW 65 in March 1945, which had two merchant ships torpedoed and sunk on their approach to Kola Inlet.

In Dutch service she was renamed the HNLMS Karel Doorman until 1948 when she was converted back into a merchantman named the Port Victor.

She was renamed Port Vindex and converted into a refrigerated cargo ship on the United Kingdom to Australia route.

HMS Campania, still in escort carrier configuration, toured around the ports of Europe as the Festival of Britain ship in 1951.