In many ways, the 2251s were modernised Dean Goods, sharing the main dimensions, but having more modern features such as taper boilers and full cabs. Increases in both boiler pressure and heating surface gave a useful increase in power at the expense of weight that restricted permitted routes. Numbers 2211–2230, built in 1940 did not have side windows. Designed by Charles Collett for medium freight and passenger duties they had 5 ft 2 in (1.575 m) driving wheels. Carrying a maximum of 3,000 imperial gallons (14,000 l; 3,600 US gal) of water to fuel a boiler operating at 200 psi (1.4 MPa) they developed 20,155 lbf (89.65 kN) of tractive effort. They could be found operating on most parts of the former GWR system. These were the first GWR 0-6-0 to use the standard number 10 boiler as later fitted to the 94xx, 15xx and various rebuilds of absorbed mainly Welsh locomotives.
Peco and Bachmann Branchline manufacture models of the 2251 in N scale and OO gauge respectively. Mainline (Palitoy) released the first ready-to-run OO model in 1978. The Bachmann model was released in 1996. It is based on the Mainline model with revised body tooling to complement a completely new chassis design that allows the boiler backhead to be modelled.