GWR has advised passengers to expect disruption on Sunday amid some last-minute engineering work that has been scheduled on the line.
No services will be calling at Bristol Parkway on Sunday, and passengers are being advised to expect longer journey times.
The warning comes ahead of late night engineering work through Swindon, which will see no trains pass through Swindon after 9.45pm on Monday, Tuesday, Wednesday or Thursday evenings.
Rail replacement buses will be operating between Didcot Parkway, Swindon and Chippenham.
GWR has advised all passengers to check the timings of services before they travel, but has warned that, due to the late notice of the Sunday works, online journey planning systems may not have been updated.
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