Production is underway at Bombardier's Derby plant and the first sets have already been delivered. The trains will enter service on the cross-London Thameslink network from next January. The class 387s have been ordered as a stopgap measure due to delays in completing the procurement of a dedicated fleet of Siemens class 700 EMUs for Thameslink. The class 387s will be redeployed on other routes when these trains enter service.