Thousands of commuters face severe disruption on their journeys home tonight, because of problems with overhead wires at Radlett in Hertfordshire.
Three train companies have been affected - Southeastern, East Midlands and First Capital Connect.
Trains are unable to run between St Pancras International and Luton on East Midlands services.
First Capital Connect is also suspended between West Hampstead and Bedford.
And Southeastern trains are suspended between Denmark Hill and Kentish Town.
More top news
Anti-fox hunting campaigners marched from on Downing Street to oppose controversial promise to hold a vote to repeal the Hunting Act.
Thousands of drivers were caught illegally using their mobile phones on London's roads following a major crackdown.
A motorcyclist is fighting for his life in hospital after a crash with a car in Kensington.