Replacement bus services are running on Southern services between Hastings and Eastbourne due to obstruction on the line at Hastings. Journey times will be extended by up to 60 minutes.
It is also affecting Southeastern services between Hastings and Tunbridge Wells.
Trains are still able to run from Tunbridge Wells towards Hastings.
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The two new owners of the South West Trains franchise have promised extra seats, new trains and faster journeys for passengers from August.
Monday afternoon's forecast for the east of the region
Monday afternoon's forecast for the west of the region