6000 4-6-0 GWR Collett King 6000 – 6029


Power Classification 7P reclassified as 8P in 1951
Introduced 1927- 1930
Designer Collett
Company GWR
Weight – Loco 89t 0cwt
               Tender 46t 14cwt
Driving Wheels 6ft 6ins
Boiler Pressure 250psi superheated
Cylinders Four  – 16¼in x 28in
Tractive Effort 40,285lbf
Valve Gear Inside Walschaert with rocking shafts  (piston valve)

The King class were the ultimate development of the GWR four-cylinder 4-6-0 engines. Stanier based his LMS Princess Royal class design on the King Class, but with an enlarged boiler and firebox necessitating a 4-6-2 wheel arrangement.

 small hall Hall class
 small modified hall Modified Hall
 small castle Castle class
 small king King class
 princess Princess Royal class

This class was designed under the direction of Collett, as an enlarged version of Collett’s Castle Class, which in turn was an enlargement of Churchward’s Star class. Churchward had proposed fitting the 6 ft 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 had been prevented from doing so due to weight restrictions on several bridges on the GWR main line. Collett’s Castle class of 1923 was therefore a compromise with a 5′ 6″ boiler. However, bridge strengthening and a better understanding of the effect of hammer blow on structures brought about by the work of the ‘Bridge Stress Committee’ set up by the Department of Scientific and Industrial Research led to the relaxation of these restrictions.

The King class was the most powerful ever British 4-6-0 design, having the highest permissible axleload of 22½ tons, and the largest firegrate (34.3 sq ft) of any British narrow firebox locomotive design. The tractive effort was regarded as important for publicity purposes and for this reason the cylinders were 16¼in rather than 16in in order to achieve a tractive effort in excess of 40,000lbf.

At the time of their construction, the GWR wanted to snatch back the honour of owning the most powerful locomotives in the UK from the Southern Railway who had just built their Lord Nelson class. The King class was built up to the maximum weight allowed on the main line. In addition, the boiler pressure and the cylinder diameter were increased and the wheels were reduced in size from the original design in order to get the required power increase. This made them the most powerful locomotive in the UK when they were built and they were able to handle the heaviest GWR expresses. Due to the size and position of their cylinders the King class engines had an unusual form of leading bogie, with the front wheels having outside bearings and the rear bogie wheels having inside bearings.

As a result of their weight they were restricted to working only the London to Plymouth lines and the London to Wolverhampton (via Bicester) line. The King class, however, were unable to serve Cornwall, due to the Royal Albert Bridge over the River Tamar being too weak for their weight, and so when they were hauling the Cornish Riviera Limited, they had to be swapped for a Castle or Hall at Devonport. Interesting the BR Britannia 4-6-2 engines were allowed to run over the Royal Albert Bridge. It was never officially acknowledged, but it was well known, that the weight of the King class engines increased from the official 89tons to 93-96tons as a result of modifications made to the locomotives during their working lives.

Because of their limited route availability only thirty were ever built, but they worked successfully on these routes.

The whole of the class was named after Kings. The names carried by 6000-6027 were in reverse order of ascendance to the throne from Richard 1 (6027) to King George V (6000). 6028 was formerly King Henry II and 6029 was King Stephen. Their names were changed in 1936 and 1937 when Edward VIII and the George VI came to the throne.

In 1927 6000 King George V visited the USA for a centenary of the Baltimore & Ohio Railway. The engine was presented with an American locomotive bell which it carried over the buffer beam when it returned to England. The original scheme for the ‘Kings’ had been to name them after cathedrals, but when the US trip was planned it was felt that a more unmistakably British icon was needed. During planning and construction of the engine was dubbed the ‘Super-Castle’.

The trip to the USA came about when the President of the Baltimore & Ohio Railway commissioned an eminent railway enthusiast (Edward Hungerford) to attend the celebration at the Stockton & Darlington Railway and report back on his observations. Hungerford met with Sir Felix Pole, the GWR general Manager, which led to 6000 going to the USA. This caused some consternation at Swindon as the first locomotive was planned to be completed by the end of September but it was required to be in the USA by August. The engine was completed with sufficient time available to complete trials and appear at a number of station exhibitions including being at Paddington on the 1st July before being shipped to America. The person in charge of the American trip was William Stanier who was the Principal Assistant to the Chief Mechanical Engineer (Churchward). Stanier became the Chief Mechanical Engineer at the LMS in January 1932 after being head hunted by the LMS Chairman (Sir Josiah Stamp). Stanier had been with the GWR since 1891 when he started as an office boy He was knighted in 1943 and when he retired in 1944 he was elected a Fellow of the Royal Society as only the third locomotive engineer after Edward Bury and Robert Stephenson to receive that honour.

6000 travelled to the USA along with the replica broad gauge engine North Star. The boiler of 6000 was loaded onto the ship separately from the frame as there was no crane available that could lift the whole locomotive. The Baltimore & Ohio Railway centenary exhibition attracted a quarter of a million visitors during the three weeks it was held. Among the visitors who rod on the footplate of the locomotive was Henry Ford.

In 1935 6014 was partially streamlined. The streamlining was removed in sections from 1937 onwards, but the wedge-shaped front to the cab was retained until 1953.

In 1947 experiments had been made with a four-row high-degree superheater in No. 6022 King Edward III, owing to a decline in the availability of high-calorific South Wales steam coal, on which the GWR had always relied for its good locomotive performance. During the 1948 locomotive exchanges, King Henry VI had 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. After this, four-row superheaters were fitted to the 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.

From 1955 onwards they were all fitted with double chimneys.

In September 1955 workings of the Cornish Riviera Express were timed and speeds of up to 108½mph were recorded on trains hauled by King class locomotives. This is the fastest authenticated speed achieved on the GWR (although 6001 King Edward VII is claimed to have achieved a speed of 109mph in 1951). The fastest post war speed record is held by LNER A4 pacific 60007 Sir Nigel Gresley in 1959 when it achieved 112mph.

The 30 locomotives in the class were allocated to five depots for working the mainline passenger expresses. The five were – Old Oak Common (London), Laira (Plymouth), Cardiff Canton. Bristol Bath Road and Stafford Road (Wolverhampton). Some very brief visits were made to Newton Abbott by two of the class during 1948 and 1949.

Although the King class were withdrawn during 1962, 6018 was steamed again in April 1963 to work a Stephenson Locomotive Society special train. They were replaced by the Western Region’s short lived diesel hydraulic Western class locomotives.

Accidents and Incidents

On the 10th August 1927 the bogie of 6003 King George IV was partially derailed whilst travelling at speed near Midgham on straight track. Fortunately, the derailment did not spread to the rest of the train.

On the 15th January 1936 locomotive 6007 King William III was hauling the 9pm express passenger train from Penzance to Paddington at a speed of between 50mph and 60mph when it came into a violent collision with a stationary brake van and five wagons. The Brake van and wagons were the rear portion of the 10:30am the special mineral train from Aberdare to Old Oak Common which was being diverted into a loop to allow the express to pass. The mineral train of 53 loaded wagons was hauled by locomotive 2802 and had become divided as a result of a breakage of a drawhook which appears to have occurred nearly two miles before the goods passed the signalbox at Shivenham.

There were thought to be about a hundred passengers on the train from Penzance. One passenger and the driver of the express were killed and 10 passengers were seriously injured and another seventeen (including the fireman) received minor injuries.

The accident occurred near Shrivenham station (about 72 miles west of Paddington) at about 5:30am whilst the express was given a clear signal to proceed.

Much of the force of the collision was taken by the frame of the goods van but the wheels of the brake van and three of the rear wagons were piled into a heap into which the express passenger engine ploughed. 6007 turned over and ended up with the boiler along the centre of the opposite track. The coupling at each end of the leading coach became unhooked and thrown sideways whilst the second coach was destroyed. The third coach was a 1929 built sleeping car which withstood the impact better and despite being derailed it kept its alignment and was not seriously damaged.

6007 King William III was officially written off, but a replacement 6007 was built using the boiler, frame and tender of the original.

The evidence from the guard (Guard H. E. Chandler, of Severn Tunnel Junction) on the goods train is copied below-

” I did not notice Marston Crossing box. I was sitting in my van engaged on other duties. I was preparing the London Division journal, and I did booking on Mr. Pole’s journal. I was also consulting my service book to see the train service back from Didcot in the event of my being relieved there . . .

I cannot therefore say the time we passed Marston Crossing, but 1 should say we were travelling at 18 to 20 miles an hour, which is the normal speed.

I cannot remember what I was actually doing when I began to realise we were slowing up, but a couple of minutes afterwards I looked at my watch and saw it was 5.15 a.m., and after a further period of five minutes I realised we had come to a stand. I looked at my watch again and it was 5.20 a.m. After coming to a stand I applied my brake very slightly.

I personally was of the definite opinion that the whole of the train was intact, and that we had come to a stand at Shrivenham home signal.

After coming to a stand, I looked through the end window of my van and sighted the Shrivenham signal box. I went through my van on to the verandah which was at the trailing end, and looked along the train with a view to seeing whether my train was intact and whether we were in fact at the home signal. It was then that I realised that my train had parted and that I only had the brake van and five wagons.

A glance to the rear a fraction later showed to my horror an express approaching on me. I gathered my flags and detonators, and, waving a red hand lamp violently, I raced to the rear, but I had not time to place down detonators.

I should say the express was about a mile or a mile and a half away when I first saw it. It is a perfectly straight road and I could see the head lights of the engine. I immediately raced back on the 6 foot side of the down main line and should say I ran back about 75 yards, but I am not quite sure of the distance. My tail lamp and side lamps were burning correctly, showing three reds to the rear. The weather was fairly good. There was a little mist in places, but nothing to speak of. I did not know the express was following me. I did not look at my watch at the time the collision took place.”

The Inspector in his report thought that the Guard was not as alert as he should have been as the train slowed down for about seven minutes. The primary blame though fell on the signalman at Shrivenham as he failed to notice that the mineral train travelling at 10-15mph was incomplete when it passed the signalbox. The signalman accepted the express into the section three minutes after the incomplete goods train passed the signalbox.


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).

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 (100 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. This would restrict it to routes which have the original GWR loading gauge, resulting in its present status preserved as a static exhibit only.

Back to GWR

Back to Locomotives