The 'Hall' Class was the result of a development that emanated originally from Churchward which saw subsequent modification by Collett, his successor, both men being CME's of the Great Western Railway.
In 1924 No 2925 'Saint Martin' (Churchward's design of 4-6-0 'Saint' Class) was selected for modification by C B Collett. the alterations to No 2925 included the fitting of 6'0" diameter driving wheels, re-alignment of the cylinders and the cab replaced by a modern 'Castle' Class one.
Further changes took place before the new 'Hall' Class began construction. The boiler pitch was modified and outside steam pipes were fitted, the locomotive was re-numbered No 4900 but retained its original name. Eighty production 'Hall' Class locomotives eventually entered service in 1928, plus a further 178 were ordered.
The locomotives saw use throughout the Great Western (and later BR (WR) region) system on mixed traffic duties often deputising for larger engines on express passenger trains. they were paired to a variety of tenders, the majority being 4000-gallon type similar to those of the 'Castle' Class.
Locomotive numbers were allocated to consecutive lots of 100 engines on construction, namely, 4900-4999, 5900-5999 and 6900-6999 with Hawksworth's 'Modified Hall' entering service as No.6959.