Rail passengers on one of the country's busiest lines had to deal with delays for a number of hours due to a signalling problem said to have been caused by cable theft.
People travelling on the Virgin Trains East Coast main line faced knock-on delays after what Network Rail described as "vandalism".
Passengers were informed on the train's tannoy system that the disruption was caused after an incident of cable theft at Darlington which in turn caused signalling problems.
Virgin Trains said in a statement: "A signalling problem at Darlington has been causing major disruption to journeys through the station this evening.
"Following an assessment by Network Rail, it was discovered that the signalling problem had been caused by vandalism."
Some services were replaced by buses, while other passengers faced delays of up to 60 minutes even when the problem had been fixed.
Anyone delayed by more than 30 minutes can apply for compensation, Virgin said.
The cost to the rail industry of cable thefts has fallen in recent years, following legislative changes through the Scrap Metal Dealers Act of 2013.
There were 845 cases of cable theft on the railways, costing the industry £12 million and resulting in 344,000 minutes of delays to services in 2011 and 2012.
Those figures had reduced in 2013 and 2014 to 179 cases, costing £2.5 million and resulting in 68,000 delay minutes.