The Modified Halls marked the most radical change to
Swindon Works' practice since
Churchward's time as
chief mechanical engineer and was very far from a simple modification of the Hall design. 'Although in outward appearance it looked almost the same, nearly everything about it was new.' Hawksworth's use of
plate frames throughout the design was a break with Churchward's practice for 2 cylinder locomotives. The cylinders were cast separately from the
smokebox saddle and bolted to the frames on each side. A stiffening brace was inserted between the frames and extended to form the smokebox saddle. The exhaust pipes leading from the cylinders to the
blastpipe were incorporated into this assembly. Additionally, Churchward's bar framed
bogie which had been adapted for the original Hall prototype in 1924 was replaced by a plate frame structure with individual springing. There were changes, too, above the running board. Hawksworth decided that the declining quality of coal reaching Great Western depots necessitated a higher degree of superheating. A larger three-row
superheater and header regulator were fitted into Swindon No.1 boiler. Improvements were subsequently made to the draughting on some engines, while others were fitted with hopper ashpans. ==Production==