The British Rail Class 387 Electrostar is a type of electric multiple unit passenger train built by Bombardier Transportation.

The class were the final rolling stock orders from the Bombardier Electrostar family with 2,805 vehicles built over 18 years between 1999 and 2017.

[4][5] On behalf of the Department for Transport, Southern issued an OJEU notice in December 2012,[4] with proposals received in January 2013.

[10] The order was announced in November 2014 with the first units on test in July 2015 and they began to enter service on 29 February 2016.

In response to this, Govia applied to the high court to seek an injunction to enable to trains to enter service,[15] and the union ultimately dropped the claim.

[18][19] The first Great Western Railway unit entered service on 5 September 2016 running between London Paddington and Hayes & Harlington in peak hours to relieve congestion on some of the country's most crowded trains.

[20][21] In January 2017 GWR began running a half-hourly Paddington to Hayes & Harlington service using pairs of these 387/1s.

[23] In January 2019, Class 387/1 EMUs began operating between Reading and Newbury after electrification works on the Reading–Taunton line were completed.

Since the December 2021 timetable change, GWR use Class 387s on daily services on the full length of the electrified sections of the Great Western Main Line and the South Wales Main Line from Paddington to Cardiff, as well as on special services when events are held at the Millennium Stadium.

[34][35] The units operated fast limited stop services from Shoeburyness to London Fenchurch Street as 12 car sets during peak hours; following the impacts of the COVID-19 Pandemic, the units were temporarily stored at Shoeburyness Carriage Sidings in March 2020.

In May 2021 c2c transferred three units to Great Western Railway owing to their fleet of Class 800s requiring repairs due to bogie defects.