Engineering work is taking place between Bristol Temple Meads and Chippenham, closing some lines on Sunday morning.
As a result, the 07:45 Bristol Temple Meads to London Paddington will start later than usual at 08:20, and then operate later than normal to arrive at London Paddington at 10:17.
Check before you travel:
You can plan your journey using the National Rail Enquiries Journey Planner.