A fire has affected rail services this morning on the line that serves Milton Keynes, Leighton Buzzard, Hemel Hempstead, Tring and Berkhamsted.
Disruption and cancellations are expected throughout today, following the incident in Harrow, north London.
A spokesman for Network Rail, which manages the UK’s rail network, said: “Owing to a fire in a commercial property next to the railway line near Harrow, train services between Watford Junction and London Euston are not running.
“Passengers wanting to travel on the West Coast Main Line are urged to check with their train operator or nationalrail.co.uk before travelling as disruption and cancellations are to be expected throughout the day.
“The safety of passengers and staff is our priority. We are working with our partners at London Midlands, Southern, Virgin Trains West Coast, Caledonian Sleeper and the emergency services to update passengers as when more information becomes available.”