GWR 4900 Hall Class

By the end of 1923 the GWR's express passenger fleet was strong, Saints, Stars, and the new Castles, but its mixed-traffic capacity was thinning. The 4300 Class 2-6-0s, capable engines in their day, were being asked to take loads beyond what their power and adhesion could comfortably manage, particularly on fitted freights to tight schedules. Churchward had recognised the gap and answered it with the 4700 Class 2-8-0, but only nine of those large freight machines were built and they were really heavy goods engines rather than all-rounders.

Charles Collett took a different route. Rather than design a new engine from scratch, he asked what would happen if a Saint was given smaller driving wheels, keeping the leading bogie that gave the Saints their good riding, while gaining the tractive effort and adhesion that smaller wheels provide. In 1924 Saint Class No. 2925 Saint Martin was withdrawn and rebuilt at Swindon with 6 ft driving wheels in place of the standard 6 ft 8½ in. The cylinders were lowered and realigned to suit the new wheel centre, and a more modern double side-window cab of the Castle pattern replaced the original Saint cab.

The rebuilt locomotive was tested for three years, undergoing minor changes including modifications to the taper boiler pitch and the fitting of outside steam pipes. By 1928 Collett was satisfied, and an order for eighty production engines was placed at Swindon under Lot 254. The production locomotives differed from the prototype only in detail: the bogie wheels were reduced from 3 ft 2 in to 3 ft 0 in, and the valve travel was lengthened from 6 in to 7½ in, both improvements arrived at during the trial period. Overall weight rose by about 2½ tons over the prototype, to 75 long tons, but tractive effort climbed from the Saint's 24,935 lbf to 27,275 lbf.

Production followed a steady cadence: Lot 254 (4901–4980) emerged between December 1928 and February 1930; Lot 268 (4981–4999 and 5900) from late 1930. The original 3,500 imperial gallon Churchward tenders were replaced from No. 4958 onwards by the larger Collett 4,000-gallon tender, which became the standard pairing for the class. Further lots ran through the 1930s and into the war years, the last (6951–6958) delivered during 1942–43. Total production of the original Hall design stood at 259 locomotives. From No. 6959 onwards Hawksworth's Modified Hall, with plate frames, individual bogie springing, and a higher-superheat boiler, replaced the Collett design, a significant departure rather than a simple update, and treated as a separate class.

The first fourteen production Halls were sent to the Cornish main line in 1928–29 as a deliberate proving exercise. The Cornish road, with its sharp gradients and tight curves, was unforgiving of any design weakness, but the new engines coped without difficulty. By the time the first eighty had been delivered in early 1930, a further 178 were on order. By 1935, 150 Halls were at work; by the outbreak of war in 1939, the class was approaching its final size and was the GWR's standard mixed-traffic engine across the entire system.

Operationally the Halls handled almost every kind of train the GWR ran. They were equally at home on a fast Paddington–Birmingham, a Plymouth–Penzance stopper, a fitted freight from South Wales to London, or a summer Saturday holiday extra to the West Country. Their nominal axle load of 18 tons 19 cwt placed them on the GWR red route availability, which kept them off the lighter cross-country and branch routes; this gap was the reason the GWR went on to build the lighter 6800 Grange (1936) and 7800 Manor (1938) classes.

The 1946 coal crisis prompted the conversion of eleven Halls (4907, 4948, 4968, 4971, 4972, 5955, 5976, 5986, 6949, 6953, 6957) to oil firing in 1946–47. While oil-fired they were renumbered into the 3900 series (3900–04 and 3950–55). All had reverted to coal firing by 1950 and resumed their original numbers.

Apart from 4911 Bowden Hall, destroyed in a Plymouth air raid in 1941, every original Hall passed to British Railways at nationalisation in 1948. BR classified them 5MT, fitted them with smokebox numberplates and the BR power class on the cabside, and worked them hard through the 1950s. Withdrawals began in March 1959 with the prototype Saint Martin, then credited with over two million miles of running across both Saint and Hall identities. The pace of withdrawal accelerated through the early 1960s as diesel hydraulics arrived on the Western Region, and the last Hall, 4920 Dumbleton Hall, was withdrawn in December 1965, marking the end of the class on BR.

4900 Saint Martin, the prototype, rebuilt from Saint Class No. 2925 in 1924 and renumbered 4900 in December 1928. Withdrawn in 1959 with a combined mileage of 2,092,500 in its Saint and Hall identities. Not preserved.

4901 Adderley Hall, first production Hall, out of Swindon in December 1928 under Lot 254.

4911 Bowden Hall, the only original Hall lost during the Second World War. On 30 April 1941 the locomotive took a direct hit during a bombing raid at Keyham, Plymouth, while stopped at a signal box, and was subsequently broken up. The crew sheltered under the signal box steps and survived.

4920 Dumbleton Hall, the last original Hall withdrawn from BR service, in December 1965; later preserved.

4936 Kinlet Hall, ran into a bomb crater near Plymouth in 1941 and was severely damaged but repaired. Built June 1929; preserved at Tyseley Locomotive Works.

4942 Maindy Hall, being 'regressed' at Didcot Railway Centre into a new-build Saint Class locomotive (2999 Lady of Legend), reversing Collett's original 1924 conversion.

4965 Rood Ashton Hall, confirmed in March 2024 to be undergoing conversion to oil firing during overhaul, becoming the first oil-fired Hall in preservation. Rescued from Barry as the presumed identity of 4983 Albert Hall; its true identity was discovered in 1998.

5972 Olton Hall, built April 1937. Selected by Warner Bros. in 2000 to portray the Hogwarts Express in the Harry Potter film series; carried lined red livery with a 'Hogwarts Railways' crest for filming. Now preserved as part of the Warner Bros. Studio Tour London exhibit.

6958 Oxburgh Hall, the 259th and final original Hall, delivered from Swindon in 1943. After this, deliveries switched to Hawksworth's Modified Hall design.

Pre-grouping inheritance (none): the class was a wholly post-grouping GWR design, with no antecedent fleet outside the parent Saint Class.

GWR era (1928–1947): the first batch was sent to the Cornish main line for proving, Penzance, Truro, and Plymouth Laira, and performed so well that further orders were placed before the first lot was even completed. From the early 1930s the class was distributed across almost every main-line GWR depot. Old Oak Common in London, Bristol Bath Road, Cardiff Canton, Newton Abbot, Wolverhampton Stafford Road, Worcester, Tyseley, Shrewsbury, Chester, and Carmarthen all held significant Hall allocations during the GWR period.

British Railways Western Region (1948–1965): the class remained the backbone of mixed-traffic working across the former GWR system. By the late 1950s and early 1960s the surviving members were concentrated at the larger Western Region depots, with Cardiff East Dock, Old Oak Common, Oxley, and Severn Tunnel Junction holding many of the last examples in service before the wholesale withdrawals of 1963–65.

GWR (1928–1947): Middle Chrome Green with black and orange lining, polished brass safety valve bonnet, copper-capped chimney, and the GWR roundel or 'Great Western' lettering on the tender. Wartime deliveries from 1942 onwards appeared in unlined plain green and, briefly, in plain black to save resources.

British Railways early period (1948–1956): BR mixed-traffic black with red, cream, and grey lining; early BR lion-and-wheel emblem on the tender. Some examples retained GWR green into the early BR period.

BR later period (1956–1965): BR lined Brunswick green, with the later BR crest. This was the most common livery worn by the class in its final years.

Oil-fired members (1946–1950): retained their running livery but carried 3900-series numbers while in oil-burning condition.

Preservation: most surviving Halls have appeared in GWR Middle Chrome Green or BR lined green at various times. 5972 Olton Hall is unique in carrying the non-prototypical lined red 'Hogwarts Railways' livery applied for filming.