There is disruption on East Coast rail line between Newcastle and Kings Cross, and between Leeds and Kings Cross, due to overhead line problems at St Neots.
Tickets are being accepted on the CrossCountry, East Midlands Trains, First Transpennine Express, and Virgin Trains services.
Replacement buses are operating between Peterborough and London, although a very limited number of trains can run via Cambridge.
Services are not expected to run via St Neots until later this afternoon, but with disruption for the rest of the day.
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