GWR 4000 Star Class

George Jackson Churchward, who became locomotive superintendent of the Great Western Railway in 1902, set out from the start of his tenure to modernise the GWR's passenger fleet on the basis of a small number of standardised classes built around two key boilers, the Standard No. 1 and the Standard No. 2. Each of his new classes was to share parts and dimensions with its sisters: a two-cylinder 4-6-0 (the Saint), a four-cylinder 4-6-0 (the Star), a 2-6-0 (the 4300 Mogul), and so on. The result, by the early 1920s, was a fleet of express and mixed-traffic engines that was probably the most technically advanced in Britain.

Churchward had studied French four-cylinder compounds in detail and had even imported three de Glehn 4-cylinder Atlantics from the Société Alsacienne in 1903 to 1905 to compare with his own simple-expansion 4-6-0s. The trial confirmed his preference for simple expansion (avoiding the maintenance complexity of compounding), but persuaded him that a four-cylinder layout, with two inside cylinders driving the leading coupled axle and two outside cylinders driving the centre axle, gave better balance, smoother riding, and more even draughting on heavy express work. The Star was the production realisation of those conclusions.

The first engine, 40 North Star, was outshopped at Swindon in April 1906 as a 4-cylinder 4-4-2 to allow direct comparison with the imported French compounds. After running trials it was rebuilt as a 4-6-0 in 1909, and the type ran in production form from 1907. 73 production Stars were built at Swindon between 1907 and 1923, in named series of ten or more (Knight, King, Star, Glorious, Princess, Abbey).

The Star's influence on later British locomotive design is hard to overstate. The four-cylinder layout, with inside and outside drive shared on different coupled axles, was lifted directly into Churchward's own GWR Castle (1923) and King (1927) classes, and into Sir William Stanier's LMS Princess Royal (1933) and Princess Coronation (1937). The Castle was specifically designed by Charles Collett as a Star with a larger Standard No. 8 boiler and modified valve gear; many of the early Castles were physically rebuilt from older Stars. As a piece of original British locomotive engineering, the Star sits at the head of every four-cylinder express design that followed.

The Stars worked the Great Western's premier express services from their introduction in 1907 until the Castles displaced them from the heaviest turns in the late 1920s. Their finest period was probably 1907 to 1925, when they handled the Cornish Riviera Express, the Cheltenham Flyer, and the Bristolian on a daily basis, and ran the GWR's competitive non-stop services on the South Devon main line and to Wolverhampton.

Once the Castle class was in service in numbers, from 1923 onwards, the Stars were progressively cascaded down to secondary expresses and to the South Wales main line. Many were rebuilt to Castles during the 1920s and 1930s; the rebuild used the existing Star frames, cylinders, and motion but fitted the larger Standard No. 8 boiler and modified the front-end. Fourteen Stars were rebuilt to Castles in this way, and one more (4000 North Star itself) was rebuilt in 1929. The remaining unrebuilt Stars worked through the Great Western's last decade as an independent company, served through the Second World War, and passed to British Railways in 1948.

Withdrawals began as a trickle in 1932 and accelerated through the 1930s and 1940s as Stars were either rebuilt to Castles or quietly retired. The class was extinct in regular service by 1957, when 4056 Princess Margaret was withdrawn from Bristol Bath Road, the last of the original Stars to remain in unrebuilt condition.

40 (later 4000) North Star, the prototype, was built in April 1906 as a 4-cylinder 4-4-2 to Churchward's pioneering four-cylinder design. After running trials it was rebuilt as a 4-6-0 in 1909 and survived in this form until 1929, when it was rebuilt to a Castle and renumbered 4000 in the Castle series. The original wheel arrangement and tender were retained at the works for a period as a museum exhibit.

4003 Lode Star entered traffic in February 1907 from the original ten-engine Knight series and was withdrawn in 1951. It was selected for preservation as the representative example of the class and is now displayed in the National Collection at the STEAM Museum of the Great Western Railway, Swindon.

4017 Knight of the Black Eagle, originally Knight of Liege, was renamed in 1914 in recognition of the German order of chivalry awarded to King George V; the original name was felt to be too closely associated with Belgium during the early stages of the First World War.

4041 Prince of Wales was the first of the Princess series and gave its name to the sub-class. Several Princess-series engines were rebuilt to Castles during the 1920s and 1930s.

The Stars were turned out from new in the original Churchward GWR middle-chrome green livery, lined out in black-and-orange and with polished brass fittings, copper-capped chimney, and full GWR coat of arms on the tender. They retained this livery essentially unchanged through the 1920s; the 1928 simplified GWR livery (without the orange line) appeared on overhauls from then on but the Stars by that date were mostly older engines and many kept their original lining until withdrawal.

British Railways from 1948 painted the surviving Stars in lined GWR-style green with the early lion-and-wheel crest. The class was extinct in regular service by 1957 and never carried the late ferret-and-dartboard crest. The preserved 4003 Lode Star has been preserved in a representative early GWR Churchward green livery since the 1960s.