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

On 22 May 2017 Class 387/1 EMUs began operating suburban services between London Paddington and Maidenhead.

On 1 January 2018, following further electrification work, Class 387/1 EMUs began operating suburban services between London Paddington and Didcot Parkway, replacing GWR Class 165 DMUs on these services.
Due to electrification being suspended from Didcot Parkway to Oxford, the previous Oxford suburban service from London Paddington was cut back to Didcot Parkway to allow electric trains to operate this service.
Oxford is still served by the fast services from London Paddington and a DMU service from Didcot Parkway.

In January 2019, Class 387/1 EMUs began operating between Reading and Newbury after electrification works on the 
Reading to Taunton line had been finished.

In December 2019, Class 345s took over most of the GWR stopping services between Reading and Paddington.
This displaced 12 Class 387s to now be used on Heathrow Express services between Heathrow Terminal 5 and Paddington.
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. In January 2017 GWR began running a half-hourly Paddington to Hayes and Harlington service using pairs of these 387/1s.
On 22 May 2017 Class 387/1 EMUs began operating suburban services between London Paddington and Maidenhead.
On 1 January 2018, following further electrification work, Class 387/1 EMUs began operating suburban services between London Paddington and Didcot Parkway, replacing GWR Class 165 DMUs on these services. Due to electrification being suspended from Didcot Parkway to Oxford, the previous Oxford suburban service from London Paddington was cut back to Didcot Parkway to allow electric trains to operate this service. Oxford is still served by the fast services from London Paddington and a DMU service from Didcot Parkway.
In January 2019, Class 387/1 EMUs began operating between Reading and Newbury after electrification works on the 
Reading to Taunton line had been finished.
In December 2019, Class 345s took over most of the GWR stopping services between Reading and Paddington. This displaced 12 Class 387s to now be used on Heathrow Express services between Heathrow Terminal 5 and Paddington.
British Rail Class 387