Caerphilly Castle was built in 1923. After only a brief period in service the locomotive was exhibited at the British Empire Exhibition at Wembley. Its travels saw it based at Old Oak Common in London, Bristol and Cardiff. It was withdrawn in May 1960 and taken into the National Collection. The locomotive was refurbished and went on display at the Science Museum in Kensington, London. After a number of years it was removed from the Museum as part of the refurbishment of its displays Caerphilly Castle spent a brief time on display in the National Railway Museum in York before transferring to its current home at STEAM in Swindon.
The video below from Youtube by gjbarnardtube includes a sequence of the walkway which goes underneath the engine and gives a unique oppprtunity to see the parts of a steam locomotive rarely seen by anyone other than those who worked on them