The King class was one of the most powerful locomotives to be built for the GWR in the 1920's. This locomotive was used for heavy express passenger services all over the west coast of England and into London. These locomotives were built to tackle the increase in passengers using the railways.
As they could reach speeds of over 60mph these locomotives were ideal for flying through Wales and Cornwall on named services like 'The Cornish Riviera Express' and 'Cambrian Coast Express'. The King class was proved to be one of the flagship locomotives of the GWR.