GWR 6000 Class

By 1918 it was apparent to the GWR Chief mechanical engineer George Jackson Churchward that his Star Class 4-6-0 locomotives would soon be incapable of handling the heaviest West of England expresses without assistance. He therefore proposed fitting the 6 ft (1.83 m) diameter boiler used on his 4700 Class 2-8-0 on to a 4-6-0 chassis, in 1919, to create a more powerful express locomotive, but was prevented from doing so by the weight restrictions on the GWR main line.[1] The future problem was therefore left for his successor, C.B. Collett to solve.

On taking up office in 1922, Collett began to develop the more powerful GWR Castle class from Churchward's Star class. However, the design was limited to a maximum axle-loading of 19.5 long tons (19,800 kg) due to the weakness of some underline bridges. The new class would not therefore be able to pull 13+ carriage express trains unaided. Following their introduction in 1923 the Castle Class was the most powerful express passenger class in the country in terms of tractive effort, but this honour was lost to the Southern Railway Lord Nelson class in 1926.[2]

The GWR's General Manager, Sir Felix Pole, was anxious for a new design that would once again enable the company to claim to run the most powerful locomotive. Pole agreed to allow Collett to explore a design for a "Super-Castle", subject to getting the tractive effort above 40,000 lbf (180,000 N).[3] By 1927 a series of bridge renewals had taken place on the Great Western mainlines. This was coupled with the widely known (but as yet unpublished) findings of the Bridge Stress Committee, which gave engineers a better scientific understanding of the impact of hammer blow, and enabled the GWR Civil Engineer to agree to raise the maximum allowable axle-loading to 22.5 long tons (22,900 kg) for the new ‘Super Castle’ class.[4]

Although Collett was nominally responsible for the design of the class, the detailed work was undertaken by his Chief draughtsman Frederick Hawksworth.[5] The bulk of the increase in power over the Castle class was initially achieved through raising the boiler pressure to a maximum of 250 pounds per square inch (1.72 MPa) and by increasing the cylinder stroke from 26 in (660 mm) to 28 in (711 mm).[6] These factors together increased the tractive effort to around 38,165 lbf (169,770 N), slightly below the figure required by Pole.

As a means of increasing the tractive effort to bring it closer to the 40,000 lbf (180,000 N) requested by Pole, smaller 6 ft 6 in (1.981 m) driving wheels were used compared to the standard 6 ft 8.5 in (2.045 m) on the "Castles" and the first six locomotives to be built had their cylinders bored out to 16.25-inch (412.8 mm) giving a further 990 lbf (4,400 N), thereby enabling the ‘Kings’ to achieve a tractive effort of 40,300 lbf (179.3 kN).[6] The smaller wheels also allowed for a wider boiler within the loading gauge to be used.

Later operational experience showed that loading gauge clearance of the outer cylinders was problematic, resulting in their replacement on each locomotive's first major overhaul, which resulted in a reduced tractive effort of 39,700 lbf (176.6 kN).

The new, 16 feet 0 inches (4.88 m) long, GWR ‘Standard No.12’ boiler was used on only this class. It had a maximum diameter of 6 feet 0 inches (1.829 m) tapering to 5 feet 6 ¹⁄₄ inches (1.683 m). There were 171 x 2 ¹⁄₄ inches (57 mm) fire tubes, and 16 x 5 ¹⁄₈ inches (130 mm) flue tubes. The firebox area was | 194 square feet (18.0 m²), with a tube area of 2,008 square feet (186.5 m²). As built, they had 96 × 1 inch (25 mm) superheater tubes.

To accommodate larger inner cylinders the distinctive design of the leading bogie was adopted, with outside bearings on the fore wheel and inside bearings on the rear wheel.

Twenty locomotives were ordered from the GWR Swindon Works in 1927 (Lot 243). The first locomotive No. 6000 King George V, appeared in June 1927. It was followed by five others (6001-6005) a month later. The remaining fourteen (6006-6019) appeared at almost weekly intervals between February and July 1928. A second batch of ten locomotives (6020-6029 Lot 267) appeared between May and August 1930.

No. 6007 King William III was written off after an accident near Shrivenham on 15 January 1936, and was condemned on 5 March 1936. A replacement was built (Lot 309) which may have incorporated some parts from the damaged locomotive; it took the same number and name, and was added to stock on 24 March 1936.[7]

It was originally intended that the class be named after notable cathedrals, but, following an invitation to feature a GWR locomotive in the Baltimore and Ohio Railroad's (B&O) centenary celebrations, the GWR decided to make them more notable by naming the class after British Kings.[5]

Following the death of King George V in 1936, No. 6029 ‘King Stephen’ was renamed ‘King Edward VIII’ after his successor; and following the abdication of the latter in the same year, No. 6028 ‘King Henry II’ was renamed ‘King George VI’ after the new King.

The class proved to be successful and able to cope with the heaviest express trains at a higher-speed timetable average than the "Castle".[8] Due to their size and weight, the King class was however restricted to the London-Taunton-Plymouth (via both Bristol and Westbury) and the London-Birmingham-Wolverhampton (via Bicester) main lines.[9] The class was therefore used on the GWR's crack expresses such as the Cornish Riviera Limited until the end of regular steam hauled express services on the Western Region of British Railways, although they needed assistance for the heaviest services over the South Devon Banks between Newton Abbot and Plymouth. They were unable to serve in Cornwall, due to the weakness of the Royal Albert Bridge, and so when they were hauling the Cornish Riviera Limited, they had to be swapped for a 'Castle' or 'Hall' at Devonport.[10]

After six months of operation, No. 6000 was shipped to North America in August 1927 to join in Baltimore & Ohio Centenary celebrations, where its sleek appearance and smooth performance impressed all who witnessed it. King George V was presented with a brass bell and cabside medallions to mark the occasion. The application of pressurised oil lubrication showed its advantages over the largely grease-lubricated American Locomotives, and was even incorporated into a later design for the B&O in 1928.

No. 6014 was partially streamlined in March 1935 with a hemispherical smokebox door, continuous splashers, straight nameplate and a swept-back cab front. However, the appendages were soon removed, with the exception of the cab.[7]

The class proved to be capable and reliable when using the high-calorific South Wales steam coal, on which the GWR had always relied for its good locomotive performance. However, during the 1948 locomotive exchanges, King Henry VI performed disappointingly using Yorkshire coal, despite demonstrating the 4-6-0 type's unique sure-footedness when climbing out of Kings Cross, where pacific types were apt to slip alarmingly.

As originally built the class had a Swindon superheater with an area of 313 square feet (29.1 m²). However, in 1947 experiments were undertaken with a four-row high-degree superheater in No. 6022 King Edward III. As a result, the four-row superheaters were fitted to the whole class, and modifications were also made to the draughting arrangement, using No. 6001 King Edward VII as a test-bed. From September 1955, double blast-pipes and chimneys were fitted, initially to No. 6015 King Richard III. Following successful testing the whole of the class was subsequently modified and, as a result, their final years in British Railways ownership saw the very best of their performance, particularly on the steep South Devon Banks at Dainton, Rattery, and Hemerdon.

The entire class was withdrawn in 1962 and replaced by the Western Region's short-lived diesel hydraulic Western Class locomotives.

There have been two serious accidents involving the class.

• On 15 January 1936, a freight train became divided at Shrivenham, Berkshire. Due to errors by the guard of the freight train and a signalman, an express passenger train hauled by No. 6007 King William III ran into the six wagons that had been left behind and derailed. Two people were killed.[11] As a result, the locomotive was written off and replaced by another with the same name and number.
• On 4 November 1940, an express passenger train hauled by No. 6028 King George VI was derailed at Norton Fitzwarren, Somerset due to the driver misreading signals. Twenty-seven people were killed and 57 were seriously injured.[12]

Thirty-one locomotives were built at Swindon, although only 30 were in service simultaneously:[13][14]

As a result of its previous 7 ft ¹⁄₄ in (2,140 mm) broad-gauge system, the GWR had the largest loading gauge of all the pre-nationalisation railways in the UK. To allow for maximum power creation and resultant speed, the GWR designed the King class to its maximum mainline loading gauge, specifically a maximum height allowance of 13 feet 5 inches (4.09 m). Consequently, this restricted them as to where they could operate under both GWR and British Railways ownership.

No. 6018 King Henry VI was the subject of preservation by Sir Billy Butlin, but the plans never came to fruition and the locomotive was scrapped.[15][16] Famous film actor Kenneth More expressed a desire to save the locomotive, but those plans never came into fruition.[17]

Developments in high-speed rail from the 1970s mean that ballast depths have increased, resulting in a present decrease in UK pan-network loading gauge height. This has recently started to be reversed with the introduction of pan-European loading gauge standards on some mainlines, mainly originating from ports. The present result of these civil engineering changes is that an original height King locomotive would not pass through various points of the modern Network Rail system, designed to a loading gauge height of 13 feet 1 inch (3.99 m).

All three preserved Kings have been on the mainline in preservation but only 6000 King George V and 6024 King Edward I have operated on the main line.

Faced with a choice of either not operating their locomotives on the mainline or modifying to allow them to pass within the current restricted UK loading gauge, private societies choose to reduce the height of their locomotives by 4 inches (102 mm) by: reducing cab and chimney height; modifying some upper pipe work. The National Railway Museum, owners of 6000 King George V, decided to keep this locomotive in its original condition.

Number	Image	Name	Owner	Current location	Current status
6000		King George V	National Railway Museum	STEAM - Museum of the Great Western	On static display.
6023		King Edward II	Great Western Society	Didcot Railway Centre	Awaiting Overhaul. Boiler Ticket Expired: 2020
6024		King Edward I	Royal Scot Locomotive and General Trust	West Somerset Railway	Overhaul underway at the West Somerset Railway. Being done to mainline standards. Boiler Ticket Expires: 2029

The Borough of Swindon commissioned a new coat of arms when it became a unitary authority in 1997. The coat of arms includes an image of 6000 King George V on the shield, recognising the importance of the Swindon works in the development of Swindon.[18] The coat of arms of the old Borough of Swindon (1900–74) included an image of GWR 3031 Class 3029 White Horse.

• Allcock, N.J.; Davies, F.K.; le Fleming, H.M.; Maskelyne, J.N.; Reed, P.J.T.; Tabor, F.J. (June 1951). White, D.E. (ed.). The Locomotives of the Great Western Railway, part one: Preliminary Survey. Kenilworth: RCTS. ISBN 0-901115-17-7. OCLC 650412984.
• Haresnape, Brian (1978). Collett & Hawksworth Locomotives: A Pictorial History. Shepperton: Ian Allan. ISBN 0-7110-0869-8.
• le Fleming, H.M. (November 1960). White, D.E. (ed.). The Locomotives of the Great Western Railway, part eight: Modern Passenger Classes (2nd ed.). RCTS.
• Nock, O.S. (1980). The GWR Stars, Castles and Kings: Part 1 & Part 2 (Omnibus ed.). London: David & Charles/Book Club Associates. ISBN 9780715379776.
• Nock, O.S. (1983). British Locomotives of the Twentieth Century Part 1. London: Patrick Stephens/London Book Club Associates. ISBN 0850595959.
• "The Office of Mayor" (PDF). Swindon Borough Council. Archived from the original (PDF) on 3 September 2014. Retrieved 27 August 2014.
• Roden, Andrew (2010). Great Western Railway - A History. Aurum.
• Trevena, Arthur (1982) [1980]. Trains in Trouble: Vol. 1. Redruth: Atlantic Books. ISBN 0-906899-01-X.
• Whitehurst, Brian (1973). Great Western Engines, Names, Numbers, Types and Classes (1940 to Preservation). Oxford, UK: Oxford Publishing Company. pp. 55, 103, 145. ISBN 978-0-9028-8821-0. OCLC 815661.

Wikimedia Commons has media related to GWR 6000 Class.

• King Class introduction (Great Western Archive)
• No. 6000 King George V (National Railway Museum)
• No. 6023 King Edward II (Great Western Society)
• No. 6024 King Edward I (6024 Preservation Society)
• Winchester, Clarence, ed. (1 February 1935), "How mighty are the Kings", Railway Wonders of the World, pp. 21–26, contemporary account of the class