2-WIM was the designation given, by Southern Railway

Southern Railway (Great Britain)

The Southern Railway was a British railway company established in the 1923 Grouping. It linked London with the Channel ports, South West England, South coast resorts and Kent...

 (SR), to a small fleet of electric multiple unit

Electric multiple unit

An electric multiple unit or EMU is a multiple unit train consisting of self-propelled carriages, using electricity as the motive power. An EMU requires no separate locomotive, as electric traction motors are incorporated within one or a number of the carriages...

s, dedicated for use on the West Croydon to Wimbledon Line. None of these units survived long enough in British Rail

British Rail

British Railways , which from 1965 traded as British Rail, was the operator of most of the rail transport in Great Britain between 1948 and 1997. It was formed from the nationalisation of the "Big Four" British railway companies and lasted until the gradual privatisation of British Rail, in stages...

 ownership to be allocated a TOPS

TOPS

Total Operations Processing System, or TOPS, is a computer system for managing the locomotives and rolling stock owned by a rail system...

 class.

Construction

The 2-WIM (2-car Wimbledon stock, numbers 1809–1812) units were rebuilt in 1929, from former Trailer First cars, originally used in ex-LBSCR

London, Brighton and South Coast Railway

The London, Brighton and South Coast Railway was a railway company in the United Kingdom from 1846 to 1922. Its territory formed a rough triangle, with London at its apex, practically the whole coastline of Sussex as its base, and a large part of Surrey...

 AC electric SL

SR Class SL

The Southern Railway gave the designation SL to the fleet of AC overhead electric multiple units used on the South London Line. 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...

 stock. They were intended for use on the line between Wimbledon and Croydon. Originally these units had some First Class accommodation in the Driving Motor car, but this was later declassified to Third Class only. The units were numbered 1909–1912 before 1936, when those numbers were reused for new 2-BIL

British Rail Class 401

The Southern Railway gave the designation 2-BIL to the DC third rail electric multiple units built during the 1930s to work long-distance semi-fast services on the newly electrified lines from London to Eastbourne, Portsmouth and Reading...

units.

Formations

Initial formations of these units were as follows:

Unit Numbers
1909–1912 / 1809–1812	9818–9821	9951–9954