LNER Thompson Class B1

LNER Thompson Class B1

61059 at Norwich Thorpe, January 1958.

Type and origin Power type Steam Designer Edward Thompson Builder Darlington Works (60) Gorton Works (10) North British Locomotive Co. (290) Vulcan Foundry (50) Build date 1942–1952 Total produced 410

Specifications Configuration 4-6-0 UIC class 2′C h2 Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge Leading dia. 3 ft 2 in (0.965 m) Driver dia. 6 ft 2 in (1.880 m) Axle load 17 long tons 15 cwt (39,800 lb or 18 t) Loco weight 71 long tons 3 cwt (159,400 lb or 72.3 t) Fuel type Coal Boiler LNER diagram 100A Boiler pressure 225 psi (1.55 MPa) Cylinders Two (outside) Cylinder size 20 in × 26 in (508 mm × 660 mm) Valve gear Walschaerts Valve type 10-inch (254 mm) piston valves

Performance figures Tractive effort 26,878 lbf (119.56 kN)

Career Operators LNER » BR Class LNER: B1 Power class BR: 5MT Nicknames Bongos, Antelopes Axle load class Route Availability 5 Withdrawn 1961–1967 Preserved (6)1264, 61306 Disposition Two preserved, remainder scrapped

The London and North Eastern Railway (LNER) Thompson Class B1 is a class of steam locomotive designed for medium mixed traffic work. It was designed by Edward Thompson.

It was the LNER's equivalent to the highly successful GWR Hall Class and the LMS Stanier Black Five, two-cylinder mixed traffic 4-6-0s. However, it had the additional requirement of having to be cheap because, due to wartime and post-war economies, the LNER, never the richest railway company, had to make savings.

Introduced in 1942, the first example, No. 8301, was named Springbok in honour of a visit by Jan Smuts. The first 40 of the class were named after breeds of antelopes and the like, and they became known as bongos after 8306 Bongo. 274 were built by the LNER. 136 were built by British Railways after nationalisation in 1948. The total number in stock at any one time however was only 409 as 61057 crashed in 1950 and was scrapped.

The prototype for the new B class (later classified B1) 4-6-0 was built at Darlington and entered service on 12 December 1942. It was the first 2-cylinder main-line locomotive constructed for the LNER since the grouping, such had been Sir Nigel Gresley's faith in the 3 cylinder layout. With cost saving a wartime priority the LNER's draughtsmen went to great lengths to re-use existing patterns, jigs and tools to economise on materials and labour. Extensive use was made of welding instead of steel castings. The boiler was derived from the Diagram 100A type fitted to the LNER Class B17 Sandringham 4-6-0s but with a larger grate area and an increase in boiler pressure to 225 pounds per square inch (1.55 MPa).

The appearance of No. 8301 (subsequently renumbered No. 1000) coincided with a visit to Britain by the Prime Minister of South Africa, Field Marshal Jan Smuts, and, as mentioned above, it was named Springbok. 18 other B1s took the names of LNER directors. Not that there were many B1s to be named during the war years: constraints on production meant that the first ten were not completed until 1944. However, Thompson then placed substantial orders with two outside builders: Vulcan Foundry and the North British Locomotive Company of Glasgow. Between April 1946 and April 1952 NBL built 290 B1s. Over the period the cost of each engine rose from £14,893 to £16,190. Vulcan Foundry contributed 50 at £15,300 apiece. Orders for the B1s, which became Nos. 61000–61409 under British Railways, totalled 410.