LSWR 46 class

The first design by William Adams, the twelve members of the 46 Class represent an interim design to supplement the Beattie Well Tanks that were already in service.[2] All were built from 1879, and were intended for light suburban passenger traffic around London and the South Coast on the LSWR railway network.[2] This was the second (and final) 4-4-0T design on the LSWR, but the first specifically intended for the London suburban services - the LSWR 318 class were built in 1875 for the routes west of Exeter and transferred to London from 1876. The 46 class were later rostered on local passenger services under the ownership of the Southern Railway, though none of the class survived into British Railways control. In consequence, none have survived into preservation.

The 46 Class was designed as a response to the requirements of the LSWR to have a range of newer, more reliable locomotives for use on their network. As a result, Adams intended the 46 Class to be an immediate stop-gap measure that could be utilised on suburban passenger services while he devised a better solution to the railway's motive power problem.[3] This solution would eventually prove to be the 415 Class of 4-4-2T locomotive.

The construction of the 46 Class was contracted out by the LSWR in order to speed construction and delivery. The contractor selected was Beyer, Peacock and Company, which manufactured 12 4-4-0 tank locomotives in 1879.[1] After only four years in service, the entire class was eventually converted to the 4-4-2 'radial' tank design between 1883 and 1886, following the successful introduction of the '415' Class in 1882 on London's suburban network.[2]

The reasoning behind the conversion was one of standardization, as various parts could be exchanged between both classes, and in consequence, the only glaringly obvious difference between the two classes, apart from the large side tanks on the 46 class, was the positioning of the safety valves on the boiler.[1] However, the conversion resulted in a heavier locomotive, as an increase in water capacity was incorporated, as was an extended coal bunker to enable longer journeys to be achieved. This entailed the extension of the locomotive's frames, resulting in a longer locomotive than the original 4-4-0 design.[1]

The class, despite its long period of service, was regarded as a stop-gap measure to assist the smooth operation of LSWR passenger services. This belief continued despite the attempt at standardization in 1883 by converting the locomotives to 4-4-2 wheel arrangement.[3] The class was eventually demoted to rural local passenger services by the LSWR, along with their 415 class cousins.[1] One locomotive, number 0376 (376), was withdrawn early in February 1914, though was sold to the Brecon and Merthyr Railway in South Wales.[2] This locomotive was re-numbered 44 when in service on this railway, passing to the Great Western Railway on 1 July 1922 who allocated it number 1391.[1] However it was withdrawn later that year before it was renumbered.[5]

The class withdrawal programme ended temporarily with the onset of the First World War, where motive power shortages effectively extended their working lives until they became surplus to requirements during the years following the war.[1] As a result, four of the class were withdrawn in November 1921, with the remaining seven examples in service just making it to grouping and Southern Railway ownership in 1923. The withdrawals continued, with the final serviceable example being withdrawn in October 1925.[3]

Because of the early withdrawal of the class during the 1920s, no examples survived to be earmarked for preservation.