The Hall class consisted of a total of 258 4-6-0 mixed traffic locomotives introduced by Charles Collett in 1928. It was designed since the 2-6-0 of the class 4300 had quickly become too weak for the increasing train weights. The prototype was rebuilt from Saint class No. 2925 “Saint Martin” with smaller drivers of six feet in 1924 and was renumbered 4900. After three years of trials, the GWR decided to order 80 more of these locomotives. So No. 4901 “Adderley Hall” was delivered from Swindon in 1928.

These locomotives still had the same superheated Churchward No. 1 standard boiler that was later fitted to the Saint class. Compared to the Saint class, the valve travel had been increased and the bogie wheels had been made somewhat smaller. The first 58 had Churchward tenders with 3,500 gallons of water seven tons of coal. The later ones had Collett tenders with 4,000 gallons and six tons.

These locomotives were very successful on topographically challenging lines like the ones in Cornwall. More and more orders followed and the last one was delivered in 1943, what brought the total number to 258. They were named after English and Welsh country houses with “Hall” in their names. In 1944, Hawksworth introduced the Modified Hall class of which 71 were built.

Between 1946 and 1950, eleven Hall class locomotives were fired with oil. All but one survived until the nationalization. Larger numbers of withdrawals commenced in 1962 and the last one was withdrawn in 1965. Eleven were preserved and all of these had been rescued from Barry Island Scrapyard. From the seven which ran in preservation, No. 4920 “Olton Hall” became famous when it was used in several Harry Potter films, carrying the name “Hogwarts Castle”. As no members of the Saint class had survived, No. 4942 “Maindy Hall” was rebuilt to No. 2999 “Lady of Legend”.