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.
More top news
Students urged to be aware of meningitis symptoms after 19-year-old woman dies just days after starting Northumbria University
The Port of Tyne is seeking planning permission to build a 25 megawatt power plant in Howdon.
An exact replica of a 1870s steam engine has been lovingly built after it's 79-year-old engineer spent 5,000 hours building it.