HMS Pegasus was an aircraft carrier/seaplane carrier bought by the Royal Navy in 1917 during the First World War. She was laid down in 1914 by John Brown & Company of Clydebank, Scotland as Stockholm for the Great Eastern Railway Company, but construction was suspended at the start of the war. The ship was converted to operate a mix of wheeled aircraft from her forward flying-off deck and floatplanes that were lowered into the water. Pegasus spent the last year of the war supporting the Grand Fleet in the North Sea, but saw no combat. She spent most of 1919 and 1920 supporting British intervention against the Bolsheviks in North Russia and the Black Sea. The ship remained with the Mediterranean Fleet until 1924, but was placed in reserve in 1925 after a brief deployment to Singapore. Pegasus was sold for scrap in 1931.

The Fairey Campania was a British ship-borne, patrol and reconnaissance aircraft of the First World War and Russian Civil War. It was a single-engine, two-seat biplane with twin main floats and backward-folding wings. The Campania was the first aeroplane ever designed specifically for carrier operations.