GWR 4073 "Castle" Class No. 4079 Pendennis Castle is a 4-6-0 steam locomotive built in 1924 for the Great Western Railway (GWR) at Swindon Works to a design of Charles Collett. It was employed on long-distance express passenger trains on the GWR and its successor, British Railways' Western Region. Pendennis Castle gained initial notoriety in 1925, when it outperformed rival engines during trials on the London and North Eastern Railway. It was bought for preservation in 1964 after covering 1.75 million miles in revenue earning service. In 1977, it was sold to Hamersley Iron, based in Western Australia, where it was shipped in the following year and operated until 1994. Upon returning to England in 2000, the engine awaited restoration at Didcot Railway Centre, its new base, which took volunteers 16 years to complete. In August 2021, Pendennis Castle returned to steam for the first time in 27 years, and will run on heritage railways across Britain. Operations No. 4079 Pendennis Castle was the seventh of a total of 171 "Castle" Class locomotives built at Swindon Works in 1923–1924 by the Great Western Railway (GWR), and designed for hauling express passenger services. It was completed in February 1924, and named after Pendennis Castle in Falmouth, Cornwall. It was allocated to Old Oak Common locomotive depot in west London. The locomotive became famous in April and May 1925, when the GWR lent it to the London and North Eastern Railway (LNER) as part of performance trials against the LNER's then new 4-6-2 A1 Class, the most famous example being No. 4472 Flying Scotsman. Running from London King's Cross to Grantham, and King's Cross to Doncaster, 4079 made the ascent from King's Cross to Finsbury Park regularly in less than six minutes, a feat the larger A1's were unable to match. Pendennis Castle was also shown to be more economical in both coal and water on the test runs, its superiority in burning unfamiliar Yorkshire coal being measured at 3.7lb per mile. Before returning to the GWR, the locomotive was put on display at the second British Empire Exhibition at Wembley Park between May and October 1925 next to Flying Scotsman, with a notice proclaiming it to be the most powerful express passenger locomotive in Britain. Back at Old Oak Common, it continued to run the routes to South Wales and the West Country until after the GWR was nationalised in 1948