The Southern Railway (SR) in the UK gave the designation SL to the fleet of AC overhead electric multiple units used on the South London Line between Victoria and London Bridge station.

These had been built by the London, Brighton and South Coast Railway in 1909, but with the abandonment of the Elevated Electric service in 1928 they were converted to DC third rail units.

After the replacement of the AC overhead equipment by the standard SR 660 V DC third-rail system on 17 June 1928,[1] these units were rebuilt.

The Trailer First cars (which had been out of EMU stock for nearly twenty years) were included in this programme, and were rebuilt into Driving Motor and Driving Trailer pairs to form four units designated 2Wim, for use on the Wimbledon-West Croydon line.

The LB&SCR purchased sufficient cars for 8 permanent sets, numbered 1E to 8E.