They were a development of Churchward's 4500 Class with larger side tanks and increased water capacity.

[2] They often are referred to as Small Prairie Class tank locomotives.

5521 was shipped to Poland in 2007 to take part in the Wolsztyn Parade, as well as briefly piloting the Orient Express.

5572 made an appearance at an open day in Reading as part of the GWR 150 celebrations in 1985, arriving under its own power.

When returning to Didcot again under its own power the engine also hauled the replica broad gauge locomotive "Iron Duke" alongside the preserved GWR Railcar W22W.