A driverless train ran for almost four miles on the London Underground during passenger traffic hours.
The incident happened around 6.45 am on Friday and passenger services were consequently diverted to allow the runaway train to pass through.
The engineering train on the Northern line went through six stops on its 13-minute journey before coming to a stop at Warren Street.
Such a major incident during rush hour could have resulted in disaster as a collision with a passenger service train leaving Archway was only narrowly avoided.
London Underground and the Rail Accident Investigation Branch are now investigating on the incident.
