This is a subject to which I’ve devoted a lot of research, but which I’ve not yet written-up in detail, so here I’ll just give an overview.
Basically, the British saw carriers as extending the search-range for the battle-fleet of big-gun warships, which would use the enhanced distance-spotting-ability of aircraft to direct their surface ships more accurately towards the enemy fleet. The British did not see carriers as being weapons to use planes to destroy enemy ships directly in the open ocean.
This stemmed from their observations of US General Billy Mitchell’s demonstration of airplanes sinking the German World War I battleship Ostfriesland on 21 July 1921, off Virginia. A US ship called the Henderson stood off to carry observers, among whom was one of my great-grandfathers, US House Representative Thomas Upton Sisson (the first, his son and grandson were named after him). He was on the House naval committee. Also aboard were Japanese and British observers.
Frankly, the Mitchell Ostfriesland test produced ambiguous results. Reasonable minds could disagree on whether the tests demonstrated that ships were now vulnerable to aircraft. The Americans and Japanese concluded that yes, warships were now vulnerable to disabling from airplanes. My great-grandfather spoke on the floor of the House that the test showed that battleships were “floating coffins.”
The British concluded they were not.
The Americans, Japanese, and British conducted tests to check their conclusions. The American and Japanese tests indicated to those navies that yes, warships could be disabled by aircraft, if aircraft could be designed for the purpose.
The British tests tended to show that warships could not be substantially disabled by planes. The British tests can, with hindsight, be characterized as having been unconsciously designed with certain biases that tended to show this result.
Note that I am saying “disabled” rather than “sink.” The British tended to think in terms of “sink only.” If an attack did not lead to sinking, it was considered not to be a very threatening attack.
However, this overlooked the fact that an air attack could destroy the command bridge and kill the control officers, and destroy the gun range-finders, and the radio-masts, and thus disable the ship.
A factor contributing to this approach by the British was the British decision to embody basically all military aircraft into a separate new service hierarchy, the Royal Air Force. This tended to bias air planners and designers away from giving focused consideration to aircraft in the maritime setting. America and Japan, by dividing air operations between the army and the navy, established a cadre of naval officers who thought about aircraft use over the seas.
And this led the Japanese and Americans to think in deep detail about developing dive bombers that could operate from aircraft carriers at sea. They both studied dive-bomber technique and then developed planes that could perform the technique. It would be Japanese dive bombers from aircraft carriers that would drive the Royal Navy from the Indian Ocean all the way to the coast of Africa in spring 1942, before the Americans at Midway in June 1942 would also use dive bombers from aircraft carriers to destroy four of the Japanese carriers that had done that to the British – which is why the Japanese navy never came back in force to the Indian Ocean.
Omitting to develop a force of carrier-based dive bombers affected the British design for aircraft carriers. The British designed their carriers to accommodate far fewer aircraft than did the Americans and the Japanese. A good dive-bomber strategy involves not just having the right kind of planes, but involves having a lot of them, so that the dive-bombers appear overhead in swarms. And a large swarm of attacking dive bombers should have a large protective escort of fighters.
In the 1930s, American admirals strove to pack the carriers with as many planes as possible.
I should now mention torpedo bombers – an area the British did not by any means overlook. We read much of the effectiveness of the biplane Swordfish and Albacore torpedo planes. British carriers were designed to carry them. But frankly, comparing them to contemporary Japanese or American torpedo planes is an embarrassing image. They are from an ancient age, showing no development in technology.
Belatedly the British tried to develop newer carrier planes (Skua, Roc, Barracuda, Seafire), but these never performed to standards set by the Japanese and the Americans.
The British justification for these design decisions, as we read it today, focuses on the needs of fighting in the North Atlantic and in the Mediterranean. And these arguments are correct. The British did not need American or Japanese style aircraft carriers to clear the Atlantic of German surface warships. Nor were such carriers needed in the Mediterranean, due to the enclosed and bounded nature of that sea.
But such carriers – or to be more precise, the dive bombers and fighters that such carriers would carry – were necessary in the large expanses of the Indian and Pacific Oceans, if the British were to maintain the entire Empire.
This leads to the second British misjudgment, which was that Japan could never develop a navy capable of threatening the holdings of the British and the Dutch. As late as 27 March 1939, Churchill himself, in a “Memorandum on Seapower” to Prime Minister Chamberlain, said
“Consider how vain is the menace that Japan will send a fleet and army to conquer Singapore. It is as far from Japan as Southampton from New York. … One can take it as quite certain that Japan would not run such a risk.”
Had this actually been true, the British would have had no need to develop American or Japanese style aircraft carriers in order to keep the Empire.
I would say that the most important role of British carriers prior to 1945, when many of them joined the Americans in the assault against Japan, was their service in ferrying fighters to Malta in the Mediterranean. Their service in this role was vital to holding Malta, which was vital to defeating the Axis in North Africa. The armoured-flight-deck design of the newest carriers was essential in enabling these carriers to survive the repeated attacks from land-based German and Italian planes. American-style carriers, with their wooden flight decks (it was the hangar deck that was armoured) would have had a tougher time surviving this.
Once the British armoured-flight-deck carriers got into the Pacific War, certain elements of British design carried significant draw-back: namely, the heat inside the ships. American carriers with open-side hangar decks were “breezier” and thus easier to keep a little cooler. Fuel capacity was also a problem: the British carriers had to go back for refueling more often. But the British carriers were much more effective in withstanding the suicidal kamikaze attacks.