LNER Pacifics

The London and North Eastern Railway (LNER) operated various classes steam locomotives with a 4-6-2 (or pacific) wheel arrangement. The LNER operated more pacifics than any other of the Big Four British railway companies, and they were mostly used for express passenger work along the East Coast Main Line, though later in their lives many were displaced to other lines.

In 1923, the LNER inherited four pacifics, to two classes each consisting of two locomotives, one class from either of two of its constituents, the Great Northern Railway (GNR) and the North Eastern Railway (NER). The Great Northern Pacifics, were of GNR Class A1, designed by Nigel Gresley and numbered 1470/1. The NER had completed two Pacifics, Nos 2400/1, designed by Vincent Raven. The LNER adopted the GNR classification system by wheel arrangement, with the A-prefix indicating the most prestigious wheel arrangement. The GNR Class A1s remained Class A1 and the NER pacifics were reclassified A2.

The LNER also classified pacific tank engines with A-numbers, and these were initially classified A5-7, and were eventually joined by a class A8. However, because of their different lineage and operational use, they are not further considered here.

The LNER completed an additional three A2s in 1924. In 1929 2404 City of Ripon was fitted with a modified A1 boiler, but otherwise the A2s bore little resemblance to the remaining LNER pacifics which were the continued evolution of the same basic Gresley design. The Raven Class A2s were all withdrawn from stock in 1936/7, freeing the A2 designation for later reuse.

Comparisons between the A1 and A2s revealed the A1s to be superior, so they were selected for more building. A total of 52 A1s were eventually built. From 1928, the A1s were started to be fitted with a higher pressure superheated boiler. This reboilering took them into Class A3, and eventually all but one of the 52 A1s would be rebuilt to Class A3, the process taking until 1948. In addition, a total of 23 new A3s (Nos 2743-51, 2595-9, 2500-8) were built.

In 1929 a single experimental Class W1 "Hush-Hush" locomotive was constructed. The W1 was rebuilt in 1936 to a more conventional 4-6-4, retaining its W1 classification. Although not technically not a Pacific, but a Hudson, there were many engineering similarities and operationally it shared similar duties.

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