The Southern Railway (SR) gave the designations 4-COR, 4-RES, 4-BUF and 4-GRI to the different types of electric multiple unit built to work the route between London Waterloo and Portsmouth Harbour.

The 4-COR type units survived long enough in British Rail ownership to be allocated TOPS Class 404.

The SR electrified the London Waterloo to Portsmouth Harbour via Woking line in the mid-1930s, and full electric services commenced over the route from April 1937.

This gave them a distinctive front-end appearance as the headcode display was placed on the opposite side of the gangway connection to the driving cab window, leading to their nickname of Nelsons (referring to Lord Nelson's eyepatch, and also to their connection with Portsmouth).

[3] Thereafter the underframes of a number of carriages were reused by the engineering department as long welded rail carriers and crane runners.

The complete 4-COR(N) 3142 was purchased by the Southern Electric Group for preservation by British Rail in 1972 and moved to the since defunct Steam Centre at Ashford (Kent).

In 1976 it was moved north to the Nene Valley Railway and helped form the opening train in 1977.