The class B1, also called Gladstone class after the first locomotive built, was one of the most powerful 0-4-2 express locomotives ever. William Stroudley had designed it as an enlarged successor of the Richmond class of 1878 to haul the heaviest express trains between London and Brighton. The first one, No. 214, was completed at Brighton in 1882. It was followed by numbers 215 to 220 and 172 to 200. The driving wheels had a diameter of six and a half feet (1,981 mm) and the cylinders measured 18.25 by 26 inches. The grate was relatively large with 20.65 square feet. 

Apart from steam-assisted reversing gear, they had pumps to feed the boiler with water that was heated by part of the cylinder exhaust steam and by the exhaust of the Westinghouse brake. Outputs of up to 1,100 indicated hp could be measured, while the running characteristics were still good at speeds of 80 mph. Sometimes they hauled trains of up to 490 tons. Stroudley died in 1889 while he was in France together with No. 189 “Edward Blount” for trials. The last class members ordered by him were completed in 1891. All locomotives built from 1889 had a boiler pressure of 150 instead of 140 psi. 

In the years after the turn of the century, the B1 class was replaced by the B4 class 4-4-0 on important express services. Ten were scrapped between 1910 and the beginning of World War I. The 26 others were taken over by the Southern Railway in 1923, but were also withdrawn between 1926 and 1933. No. 214 was preserved as the only LB&SCR tender locomotive and is now on static display in the National Railway Museum, York.