There are delays of up to 40 minutes on First Great Western trains between London Paddington and Bristol Parkway due to an earlier signalling problem at Southall.
First Great Western advise of delays until around 2pm.
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Jeremy Corbyn's visit has been one of the big talking points of another busy day at Glastonbury.
The Labour leader said socialist politics would not be put "back in a box" as he appeared on stage at the festival.
Turning windier with a few showers