In July 2015, London Overground announced an order for 45 new Class 710 units, some of which would displace the Class 378s in use on the Watford DC line. These displaced units will then be cascaded to strengthen services on the other lines the units are used on. In 2018, London Overground began a programme to refresh the Class 378 fleet, giving them a livery and moquette similar to the Class 710. Innovations for the passenger are air-conditioning, real-time passenger information systems, wheelchair access, the ability for level access, and different seat moquette colours to highlight priority seating. External CCTV is displayed automatically on releasing the doors via an in-cab monitor, removing the need for "Driver-Only Operation" (DOO) equipment such as monitors/mirrors at platforms. This is similar to that already used on Southern's "Electrostar" units. If a passenger operates an emergency alarm, the internal CCTV is displayed to the driver on the in-cab monitor, so that they can view the affected area of the train (in addition to speaking to the person). The Class 378 fleet is currently formed of two separate subclasses, DC-only 378/1 and dual-voltage (AC and DC) Class 378/2:    In February 2013, approval was gained for the procurement of 57 additional vehicles to lengthen the Class 378 fleet from four to five cars. TfL's Business Plan provides for the start of five-car services on the East London line from November 2014, and on the rest of the electrified Overground network by the end of 2015. In January 2016, TfL announced that all 57 units were now running with five cars. In December 2018, unit 378 232 was shortened back to four cars to run on the Gospel Oak to Barking line while delays to delivery of are resolved. 378 206 and 378 209 were also shortened to 4 carriages, as temporary cover when the class 172s went off-lease.