The GWR locomotive standardisation policy pursued by George Jackson Churchward envisaged a range of locomotive classes which would be suitable for the majority of duties, and yet which would share a small number of standard components.

Collett, (Churchward's successor at Swindon Works) rather introduced the Hall class with 6-foot (1.829 m) diameter driving wheels.

The 4300 Class of 2-6-0 tender locomotives had been introduced on the GWR for mixed traffic duties in 1911, and by 1932 there were 342 in service.

[3] However, by the mid 1930s some of the earlier examples were in need of attention and the class as a whole was struggling with some of the duties expected of them.

Collett therefore revived the Churchward proposal, but modified the design to include a cab and controls to the current style.

[4] Their smaller driving wheels giving them a higher tractive effort than the Hall Class.

As a result, a lighter version in the form of the Manor Class was introduced for these duties.