The prototype for the new B class (Later classified B1) 4-6-0 was built at Darlington and entered service on the 12th of 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 .
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, 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 Railway auspices, totalled 410.
The B1s operated throughout LNER territory; the first batch was distributed among depots on the former Great Eastern Railway section: Ipswich, Norwich, and Stratford in London. They were an immediate success and were soon working the Liverpool Street - Harwich boat trains, the Hook Continental and the Day Continental. B1s were also a familiar sight on other top-link workings such as The East Anglian, The Broadsman and The Fenman. During the 1950s over 70 B1s were stationed on ex-GE lines.
They enjoyed similar popularity on ex-Great Northern and Great Central territory with engines based at Darnall, Sheffield, regularly rostered for the Master Cutler and South Yorkshireman expresses. Elsewhere there were substantial allocations in Scotland, West Yorkshire and on Humberside.
If any faults were to be highlighted on the B1, it must be the ride quality. O.S. Nock, the famous railway author, often criticised the B1s for a poor ride, not somehting many were used to on the Gresley engines. The B1 was very cheap to build, but the final result was an engine that was somewhat lacking in the quality the LNER men had come to expect. The Two Cylinder layout gave the engines good starting power and excellent hill climbing abilities, but it also caused very bad hunting effects, a result of the use of cut-offs of up to 75% (a 10% advance on Gresley engines), and as such they were less kind on the passengers they carried than the B17's they replaced.
Overall however, it was entriely necessary that the B1s be introduced. The LNER was operating a high number of engines that were well past their economic life, even if it did mean many of them were lost before the preservation movement began. It was somewhat ironic that the engines that came under threat with the arrival of the B1s were the ones that Thompson admired the most: the engines of the North Eastern Railway (those of his Father-in-Law).
Sadly, with the change in the policies of British Railways, the B1s were withdrawn long before their projected economic working life. The first to be withdrawn was No.61085 in November 1961. Officially the whole class was rendered extinct in September 1967. Two were saved for preservation. See below for more information.
Early B1s were named after species of antelope, whilst later engines were named after directors and board members of the LNER. This lead to the fact that the B1 class contained the shortest name given to a British locomotive (#1018 'Gnu') and one of the longest (#1221 'Sir Alexander Erskine-Hill').
|-||1089||61189||Sir William Gray|
|-||1215||61215||William Henton Carver|
|-||1221||61221||Sir Alexander Erskine-Hill|
|-||1237||61237||Geoffrey H. Kitson|
|-||1242||61242||Alexander Reith Gray|
|-||1243||61243||Sir Harold Mitchell|
|-||1245||61245||Murray of Elibank|
|-||1246||61246||Lord Balfour of Burleigh|
|-||1250||61250||A. Harold Bibby|
|-||-||61379||Mayflower||Name carried by preserved 1306.]]|
Two have been preserved