A points failure has caused severe disruption for passengers at Euston station.
The issue, reported at about 10:45am on Sunday, led to no trains entering or leaving the station for several hours.
Avanti West Coast, London Northwestern Railway and London Overground services on the route were all affected.
The lines reopened by early afternoon but major disruption was still expected to continue until the end of the day.
Points can fail if they get clogged with debris or ice, the drive mechanism fails or they expand too much in hotter weather.
Euston station hit the headlines in recent weeks after the Government made changes to the HS2 railway, where it is expected to terminate.
Prime Minister Rishi Sunak said the management of HS2 would no longer be responsible for the Euston site, with the Government instead looking for investment from the private sector.
