There is major disruption to Cross Country services between Oxford and Didcot Parkway, Bridgwater and Taunton, and Taunton and Plymouth/Penzance.
First Great Western said it would only be able to run four trains an hour between Reading and London Paddington this morning because of flooding near Maidenhead. South West Trains, Southeastern and Southern are also operating heavily-curtailed services.
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A one ton horse has had to be airlifted to safety by crane after getting stuck in mud in Dorney.
Friday's forecast for the east of the region
Friday's forecast for the west of the region