No 5637 was built in the GWR Swindon Railway Works to a design by C.B.Collett. It went into service at the Cardiff Cathys shed in September 1925 for it's running in period. In November 1925 it was allocated to Barry followed by
Abercynon in October 1928, Radyr in September 1955, and Treherbert in October 1955. 5637 ended up back at the Barry Shed in March 1960 where it was withdrawn from service in June 1964.
The locomotive was purchased for scrap by Woodhams Brothers and taken to the
Barry Docks Scrap Yard where it was acquired for preservation by the
Birmingham Railway Museum. 5637 was thus taken by rail to Tysley in 1974 from where it was purchased by Thamesdown Council and moved to the Swindon and Cricklade Railway in April 1982. The locomotive was subsequently purchased outright from Thamesdown by the 5637 Steam Locomotive Group headed by members of the Swindon and Cricklade Railway.
The 56xx class locomotives were introduced to haul coal and passenger traffic
over the South Wales Valley Lines. They were a development of the pre-grouping
companies 0-6-2T engines which combined a high tractive effort with a short
wheel base enabling them to negotiate the tight curves in the Welsh valleys.
Many standard Swindon components were used, such as the No. 2 boiler, and
the 56xx class of engine first entered service in December 1924. There were
originally 200 engines in this class, the second hundred being numbered 66xx.
Only 9 members of the 56xx class have survived to the present day and 5637 is
the only one currently in service.