A signalling fault between Milton Keynes Central and Watford Junction is causing major disruption to trains heading into London Euston.
Trains may be cancelled or delayed by up to 80 minutes with major disruption expected until 12:00.
Avanti West Coast says that passengers travelling between Edinburgh, Glasgow, Blackpool, Liverpool, Manchester, Holyhead and London Euston may use CrossCountry, Chiltern Railways, East Midlands Railway, London North Eastern Railway, London Northwestern Railway, ScotRail and TransPennine Express services to complete their journey.
London Northwestern Railway have ticket acceptance in place with Avanti West Coast, Chiltern Railway, East Midlands Railway, London Overground, London Underground and Thameslink.
Rail replacement buses have been requested between Northampton and Watford Junction.
Please check National Rail Enquiries for the latest travel advice.
