The trains will be assembled at Bombardier's Derby plant and are due to enter service in 2016, when they will replace the fleet of class 442 EMUs currently used on these services.

Bombardier is currently delivering an initial batch of 29 four-car class 387/1s to GTR and these trains will be introduced on Bedford – Brighton Thameslink services from next month. The class 387s were ordered as a stopgap due to delays in completing the procurement of a dedicated fleet of Siemens class 700 EMUs for Thameslink.