GWR 111 The Great Bear

By 1908 the Great Western Railway under G. J. Churchward had built up a powerful express portfolio with the Saint Class 4-6-0 and the developing four-cylinder Star Class. Continental and American railways were experimenting with larger 4-6-2 (Pacific) engines, and Churchward, always alert to the latest engineering practice, wanted to evaluate the type in British conditions.

The result was No. 111 The Great Bear, designed during 1907 and completed at Swindon Works on 14 February 1908. The engine was Britain's first 4-6-2 Pacific. It used four cylinders in the same divided-drive arrangement as the Star Class but with a much larger boiler and a wide firebox supported by a trailing axle. The boiler was the largest ever fitted to a British locomotive at the date of construction, over a quarter wider than the Saint's and with almost half as much again grate area.

The Great Bear was named for the constellation Ursa Major, in line with the GWR's tradition of naming groundbreaking engines after astronomical bodies (the company's North Star, Lord of the Isles and other celebrated singles had carried similar names). The press of the day made much of the engine's symbolic importance. It was widely photographed.

In service, however, the engine's very size proved its undoing. Its weight required bridge strengthening on the Paddington–Bristol main line, work that was undertaken, but elsewhere on the GWR network the bridges and curves could not accept it. The engine was therefore confined to a single route. Combined with adequate performance from Churchward's production Saints and Stars, this operational limitation killed any plans for follow-on Pacifics. The GWR placed no further Pacific orders, and the Great Bear remained unique. Britain would not see another GWR Pacific.

The Great Bear worked the Paddington–Bristol expresses from spring 1908 until late 1923. Performance was steady but the engine was rarely pushed to its theoretical limits, the timings of the Paddington–Bristol services did not require its full capability. Drivers reported that the engine rode well at speed and steamed freely, but the unique boiler was a maintenance burden because no other engine could share its parts.

By 1923 the boiler had reached the end of its useful life and required either a complete rebuild or scrapping. Charles Collett, who had succeeded Churchward as GWR CME in 1922, decided that the Pacific arrangement should not be perpetuated. Rather than build a second unique Pacific boiler, the engine was rebuilt at Swindon in September 1924 as a Castle Class 4-6-0 (one of the first batch of Castles), retaining its number 111 but renamed from "The Great Bear" to "Viscount Churchill". The original Pacific boiler was scrapped, there was nothing else on which to fit it.

As a Castle, No. 111 Viscount Churchill ran for a further twenty-nine years, working the principal GWR and BR Western Region expresses to the West of England and South Wales. The frames had been cut to suit the Castle wheelbase and certain ancillary fittings retained, but the rebuild was sufficiently extensive that it is sometimes treated in GWR records as a new engine.

The rebuilt engine was withdrawn from BR Western Region service in July 1953 and scrapped soon afterwards. No part of either the original Pacific or the rebuilt Castle is preserved. The Pacific's identity survives only in photographs, the surviving design drawings at the National Railway Museum, and the contemporary press coverage of its 1908 introduction.

Unique British 4-6-2 Pacific outline of 1908, immediately distinguishable from any contemporary British engine by its 4-6-2 wheel arrangement, exceptional length, and very large boiler. Carried the standard GWR copper-capped chimney, brass safety-valve cover, and Middle Chrome Green livery. The trailing carrying axle, supporting a wide firebox extending behind the rear coupled wheels, was the key visual departure from the Saint and Star 4-6-0s. The engine carried its name "The Great Bear" on a brass nameplate over the centre splasher and the GWR coat of arms on the leading splasher.

111 The Great Bear (1908–1924), the unique original Pacific, completed at Swindon on 14 February 1908. The first Pacific (4-6-2) wheel arrangement in Britain. Worked the Paddington–Bristol expresses for sixteen years.

111 Viscount Churchill (1924–1953), the rebuilt Castle Class 4-6-0 retaining the same number. The rebuild reused the Pacific's frames (cut to fit the Castle wheelbase) and certain ancillaries, but the Pacific's unique boiler was scrapped, there were no other engines on which it could be re-used. Withdrawn in July 1953 with a combined two-identity mileage of approximately 985,000.

1908–1924 (as Pacific): exclusively allocated to Old Oak Common in London for working the Paddington–Bristol expresses. The engine's weight and length prevented its operation elsewhere on the GWR system.

1924–1953 (as Castle Class No. 111 Viscount Churchill): after rebuilding the engine entered the wider Castle Class allocation pool, working the principal GWR expresses to the West of England, South Wales, and Birmingham/Wolverhampton. Allocated successively to Old Oak Common, Newton Abbot, Cardiff Canton and Stafford Road during its Castle career.

1908–1924 (as Pacific): standard GWR Middle Chrome Green with black-and-orange lining, polished brass safety-valve casing, copper-capped chimney, and "The Great Bear" nameplate over the centre splasher. The GWR coat of arms appeared on the leading splasher.

1924–1953 (as Castle): standard GWR/BR Castle Class livery, Middle Chrome Green during the GWR period, BR Brunswick green from 1948, with the late BR crest from 1956 (briefly) before withdrawal in 1953.