The SR N15X class or Remembrance class were a design of British 4-6-0 steam locomotives converted in 1934 by Richard Maunsell of the Southern Railway from the large LB&SCR L class 4-6-4 tank locomotives that had become redundant on the London–Brighton line following electrification. It was hoped that further service could be obtained from these locomotives on the Southern's Western Section, sharing the duties of the N15 class locomotives. The locomotives were named after famous Victorian engineers except for Remembrance, which was the LBSCR's memorial locomotive for staff members who died in the First World War. In their new form the locomotives were similar in outline to the N15 class, though suffered from the expectation amongst crews that they were an improved version of this type. Despite this, their ability to accelerate well was put to good use on cross-country trains between main lines. The class saw service into nationalisation in 1948. All had been withdrawn by 1957, with none preserved. Background With the impending electrification of the Southern Railway's Central Section (the former LB&SCR lines), the question arose as to what to do with the relatively new and powerful LB&SCR designs. Maunsell looked at the possibility of converting the LB&SCR “Remembrance” or L Class 4-6-4 tanks built by L. B. Billinton between 1914 and 1922. These Baltics had proved to be capable machines on the Brighton line, although their relatively low boiler pressure (), the excessive difference between "first valve" and "second valve" on the regulator, and more particularly their small () piston valves in relation to their large () cylinders were a significant limitation, precluding their use on any other part of the Southern system. The limited coal and water capacity also limited their range, though adequate for the short runs on the Brighton line. The decision was taken to rebuild them into more conventional 4-6-0 tender locomotives. Conversion All seven of the Billinton L Class locomotives entered Eastleigh works in 1934 for rebuilding, each leaving the works the same year. Conversion into the 4-6-0 tender type, entailed removing the trailing bogie, water tanks, and bunker, shortening the mainframes and fitting new cabs; these were of the side-window variety already used on the Lord Nelson class. At the same time there was a revision of the locomotives' front end arrangement incorporating a "King Arthur" N15 type of blast pipe and chimney; boiler pressure was increased to , whilst