4-6-0 Steam Locomotives in Great Britain

Class S69/B12 (Locobase 2374)

Data from "Great Eastern Railway," Locomotive Magazine, Volume 18 (15 January 1912), p. 3; and "Six Coupled Bogie Express Engine, Great Eastern Ry"(15 February 1912), p. 30. See also E L Ahrons, The British Steam Locomotive from 1825 to 1925 (London: Richard Tilling, 1927), pp. 334. [], [] and from Richard Marsden's [] (15 February 2004). For a full description of Paxman's promotion and production of Lentz gear for British and overseas customers, see "Lentz Valves for Locomotives" on Richard Carr's Paxman History Pages at [], last accessed 9 August 2021. (Thanks to Alexander Blessing for his 31 May 2026 email correcting the total engine and tender wheelbase, and engine and tender weights.)

A high-wheeling express passenger Ten-wheeler, the 1500 repeated S D Holden's earlier 4-6-0s Its design featured an all-inside cylinder layout with modest dimensions, Belpaire firebox, 10" (254 mm) piston valves, and typically undersized superheate.. Note that the tube length is quite short because the firebox sat low between the second and third axles. The footplate crew occupied a commodious cab. The 1912 report for LM noted that the second locomotive of the first batch (1501)was the 1,500th locomotive built at Stratford Works since it opened in 1851.

Glover (1967) reported that this class "performed with marked success over the somewhat light road for which they were planned." OS Nock (RWC IV, pl 159) weighed in with "The new engines were an immediate and resounding success, and their increased haulage capacity over the 4-4-0s was of immense value during the war years when loads were greatly increased over previous standards."

After the war, the GER contracted with aspiring Clydebank builder William Beardmore & Company to produce 20 of the class. (Works numbers were 134-153 in 1920.)

The last 10 were completed with Lentz poppet valves by Beyer, Peacock for the East Anglia lines of the Great Eastern. Classed as B12/2 by the LNER, this class's valve gear proved problematical and the engines were reworked with Stephenson link motion in 1933. See Locobase 3766 for the B12/3 large-boiler rebuild.

In the meantime, B12s went all over England. Thirty-one went to Scotland where they pulled the heaviest of passenger trains. Marsden observes that the LNER exploited the class's light axle loading and relatively compact dimensions (including a short wheelbase) on a variety of services such as the American ambulance trains bringing wounded back from France.