The British Rail Class 456 electrical multiple units were built by BREL at York Works from 1990-91. 24 two-car units were built as direct replacements for the elderly Class 416 2EPB units which operated on the Central Division of the Southern Region of British Rail. Units were delivered into traffic painted in Network SouthEast blue, red and white livery.

Units were numbered in the range 456001-024. Each unit consisted of two carriages; a driving motor and a driving trailer. The technical description of the unit formation is DMSO+DTSO. Individual carriage numbers were as follows:

• 64735-64758 - DMSO
• 78250-78273 - DTSO

When first introduced, the units suffered from many technical and reliability problems, which delayed the replacement of the 2EPB units. However, once they settled down the units were used on many services, including London Bridge to London Victoria via Crystal Palace, and London Victoria to Horsham. Before the lines closed in 1997 to allow the building of the Croydon Tramlink, Class 456 units worked services on the Addiscombe branch, and from East Croydon to Wimbledon.

Current Operations

Since the privatisation of Britain's railways, the entire Class 456 fleet passed into the South Central Trains franchise, which was originally won by Connex. Only one unit, no. 456024, was repainted in white and yellow Connex livery, when it was named Sir Cosmo Bonsor after a chairman of the South Eastern Railway. The rest of the fleet remained painted in NSE livery.

In 2000, Connex lost the South Central franchise to the Go-Ahead Group, who rebranded the company as Southern in 2004. It is currently planned that the Class 456 fleet will undergo refurbishment work commencing in 2005.