Engineering work is taking place between Harlesden and Hemel Hempstead, closing all lines from 20:10 on Saturday and on Sunday.
From 20:10 on Saturday until the end of service, trains between East Croydon and Milton Keynes Central will run between Clapham Junction and Shepherds Bush only.
On Sunday, no trains will run between Clapham Junction and Watford Junction.
Customers should use alternative Southern services between Clapham Junction and London Victoria, London Underground services between Victoria and Euston, and London Northwestern Railway services between London Euston and Watford Junction / Milton Keynes Central.
Check before you travel:
These changes are not currently shown in the National Rail Enquiries Journey Planner, please check back nearer to the time of travel.
You can plan your journey on London Underground by using the Transport for London Journey Planner