Steam locomotive and tender, Great Western Railway 4-6-0 No 4073 "Caerphilly Castle".

Built at Swindon works in 1923, Caerphilly Castle is the prototype for Great Western Railway’s (GWR) Castle class. Castle class locomotives were built between 1923 and 1950 - no other British class of express passenger steam locomotive was built over such a long period.

At the beginning of this construction period GWR was a leader in British locomotive design. However, arguably, they then rested on this success and were overtaken by the developments of other companies. The continued construction of four-cylinder 4-6-0 locomotives after the Second World War was certainly rare.

The Castle class is fundamentally an enlargement of the outstanding Star class of 1907 (No.4003 Lode Star is preserved in the National Collection). The Castle class itself was subsequently enlarged in 1927 to produce the King class (No.6000 King George V is preserved in the National Collection).

No. 4073 was withdrawn from service in 1960, although the locomotive was due to retire five years earlier in 1955.

Caerphilly Castle entered the National Collection in 1961.

https://en.wikipedia.org/wiki/GWR_4073_Class_4073_Caerphilly_Castle