The British Rail Class 460 Coradia Juniper (8-GAT) was a class of electric multiple-unit passenger trains built by Alstom at Washwood Heath between 1999 and 2001. They were part of Alstom's Coradia Juniper family, which also includes Classes 334 and 458.

For the entirety of their service life they operated Gatwick Express services between London Victoria and Gatwick Airport. Following their withdrawal by Gatwick Express in 2012, the fleet was merged with the mechanically similar Class 458 fleet and extensively rebuilt to form a fleet of 36 units—designated Class 458/5—that are now used by South Western Railway.

National Express (NX) began operating the Gatwick Express franchise in April 1996, having been awarded a 15-year contract to do so by the Director of Passenger Rail Franchising as part of the privatisation of British Rail. The company was required as part of the award to replace the existing Gatwick Express rolling stock, which had already been in service for more than 12 years when National Express had inherited it from British Rail. Accordingly, NX and rolling stock lessor Porterbrook placed an order with Alstom for the construction and delivery of eight eight-car units, enough to run services at 15-minute intervals at peak times.

All eight units, numbered 460001–460008, were manufactured at the former Metro-Cammell works at Washwood Heath in Birmingham, which Alstom had acquired in 1989. Each unit was formed of two motor cars with driver's cabs, three intermediate motor cars, and three intermediate trailer cars. One driving car, coded DMLFO and usually kept at the London end of the train, consisted of a large luggage compartment and a small section of first-class seating, while the other driving car was fitted with standard-class seating throughout. The fibreglass nosecones—which earned the class the nickname Darth Vaders among some rail enthusiasts—concealed the anti-climbers and an emergency coupler. One bogie on each motor car was fitted with traction motors.

Delivery of the new units began in 2000, but their entry into service was delayed by a number of defects – particularly concerning the braking systems, air-conditioning, and Train Management System (TMS) software. Only after an extensive program of repairs and modifications by Alstom did the fleet's reliability reach a level sufficient to allow full withdrawal of the ex-BR stock in 2005.

On 22 June 2008 the lease for the Class 460 fleet was transferred to Southern when the standalone Gatwick Express franchise was merged into the Southern-operated South Central franchise, as part of a plan to use Gatwick Express services to provide extra capacity on the Brighton Main Line south of Gatwick Airport. Because the Class 460 fleet was too small to support both the extension to Brighton and the existing 15-minute frequency, Southern leased and refurbished a number of Class 442 units to work alongside the Coradia Junipers when the extended timetable took effect in December 2008.

Following the June 2009 renewal of their contract to operate the South Central franchise, Southern leased and refurbished the remainder of the Class 442 fleet for use on Gatwick Express services. This enabled the gradual withdrawal of the Class 460 fleet, which began in 2010 and was completed by September 2012.

South West Trains, operator of the South Western franchise from 1996 to 2017, had been experiencing a considerable shortage of passenger capacity on many of its suburban routes in the years immediately prior to 2012, which it attributed primarily to the fact that passenger numbers had increased dramatically without a corresponding increase in the size of their fleet. The company had suggested to the Department for Transport on at least three occasions that their fleet of Class 450 units should be enlarged, but had been turned down each time.