Built in 1927, the Great Western Railway (GWR) 6000 Class (King Class) were a 4-6-0 type of locomotive designed for passenger service. Aside from single pacific type unit built in 1908 (The Great Bear), the King Class locomotives were the largest locomotives built by the GWR. They were named after the kings of the United Kingdom / England.
Designed by by Chief Mechanical Engineer C. B. Collett the locomotives featured four cylinders - 2 outboard and 2 inboard. The inboard cylinders completely occupied the space so the bearings of the lead wheels were relocated to the outside of the wheels. This gave the lead truck of the King Class their unique appearance.
To increase the tractive effort the driving wheels diameter was set at 78" and the first six locomotives to be built had their cylinders bored out to 16.25-inch. This provided an initial tractive effort of 40,300 lbf. Operational experience later showed trouble with the loading gauge clearance of the outer cylinders. They were replaced at the first major overhaul resulting in a reduced tractive effort of 39,700 lbf. The Kings provided outstanding performance over their service life but their operation on the system was somewhat limited due to their high axle load.
The lead locomotive of the class is #6000 "King George V". It was in operation for only six months when it was shipped to the United States to take part in the Baltimore & Ohio Railroad's centenary celebration in August of 1927. The locomotive was presented with a brass bell and medallions mounted on the side of the cab to mark the occasion. All were impressed with the locomotive's performance and its sleek appearance.
Over the years modifications were made Four-row super-heaters were fitted to the whole class in 1947 and double blast-pipe exhaust was fitted from 1955. Their final years in service under British Railways ownership saw the very best of their performance.
After the class was retired in 1962, a number of the locomotives were preserved, "King George V" was restored and operated on the main lines for many years. Need for a costly overhaul eventually forced the locomotive into retirement. "King George V" is preserved today at the Swindon "Steam" Railway Museum.