In 1850, the LSWR decided that the London suburban passenger services should be operated using small tank locomotives.

To determine the most suitable type, Joseph Hamilton Beattie, the LSWR Mechanical Engineer, prepared a series of designs for six-wheeled well tank locomotives, each of which incorporated one or more differences from the previous class.

[1] Having chosen the most suitable characteristics, Beattie prepared a standard design of 2-4-0WT with 5-foot-6-inch (1.676 m) driving wheels and cylinders 15 by 20 in (381 by 508 mm), bore by stroke; and the LSWR began to take delivery of these in 1863.

[2] The new design eventually totalled 85 locomotives; most came from the Manchester firm of Beyer, Peacock and Company between 1863 and 1875, but three were built in the LSWR workshops at Nine Elms during 1872.

The three Nine Elms locomotives, and the last six of 1875, exhibited more obvious detail differences compared to the other 76: the leading wheels were 3 ft 7+3⁄4 in (1.111 m) diameter instead of 3 ft 6 in (1.07 m); two of the four safety valves were larger; but the most noticeable difference was that the splashers were rectangular instead of round.

Some of their new duties required a greater water capacity than the tanks could contain, and so 31 were converted to tender engines between 1883 and 1887;[11] these were withdrawn between 1888 and 1898.

These three remained in service because of the sharp curves of that railway's freight branch to Wenford Bridge, which carried China clay traffic to the main line.

[18] Not every loco was transferred to the duplicate list - several were withdrawn whilst carrying their original numbers.

Number 298 (later renumbered 30587) is owned by the National Railway Museum (NRM) and is loaned to, and normally based at, the Bodmin and Wenford Railway, however it was at the NRM for six months (from July 2018 until January 2019) hauling brake-van rides in the South Yard.