Tractive effort started out at 29,775 lbf (132.45 kN) but was increased substantially in the production engines by enlarging the cylinder diameter to 18+1⁄2 in (470 mm) and raising the steam pressure to 225 lbf/in2 (1.55 MPa).

Other modifications centred on improving the weight distribution, altering smokebox lengths and fitting larger diameter chimneys.

The 84 2800s built by Churchward were constructed over more than a decade and remained the GWR's principal long haul freight engines throughout the 1920s and 1930s.

[2] The 2800 class was particularly used for hauling heavy trains of coal from the South Wales coalfields to the large conurbations served by the GWR, and large numbers were allocated to sheds in South Wales, but the type was the main heavy freight type on the GWR and was used across the network.

Due to the variety of freight flows it was found that individual locomotives could spend extended periods away from their home shed and a container was added to the left hand valence which carried details of boiler washout dates to ensure that this necessary activity was carried out in a timely manner.

At the outbreak of World War II, an order was placed for 60 additional locomotives for use in France, but this was cancelled following the evacuation at Dunkirk, the 10 engines that had already been completed being included in the GWR stocklist.[2][relevant?]

Between 1945 and 1947, coal shortages caused GWR to experiment with oil fired 2800 locomotives and 12 of the 2800 class were converted.

The experiment, encouraged by the Government was abandoned in 1948 once the extra maintenance costs were calculated and the bill had arrived for the imported oil.

[11][12][13] 2861, built in 1918, was one of the "Barry Ten" and eventually broken up for parts at the Llangollen Railway in 2014 and the frames scrapped.