Thousands of train passengers have endured travel misery on a key London to Scotland route with the severe disruption likely to last all day.
Caused by an overhead wire collapse on the East Coast in Cambridgeshire, the problem led to some passengers spending Tuesday night on a train at London's King's Cross station.
East Coast services were severely disrupted, with no trains able to run between Peterborough and London during the morning. Services run by First Capital Connect, Grand Central and First Hull Trains were also affected
As Network Rail (NR) and East Coast explained what had happened, Bob Crow, leader of the RMT transport union, said he had been warning about a shortage of overhead line crew and capacity for "years".
With the last East Coast train from King's Cross cancelled on Tuesday night, the station remained open all night as passengers trying to get home refused to leave the train. They included football fans trying to get home from Arsenal's Champions League match with Bayern Munich. The London Evening Standard said a decision had been made to let the passengers stay on the train.
The trouble on Wednesday followed severe disruption last week caused by an overhead line problem at Radlett in Hertfordshire.
At the same time as passengers were being delayed, the Office of Rail Regulation was issuing a damning report on NR's recent performance, accusing the company of "areas of poor management of the railways" and instances of "basic operational planning mistakes".
A spokesman for NR said: "At around 10pm yesterday a train driver reported problems with the overhead power lines near St Neots in Cambridgeshire, on the East Coast Main Line.
"Upon investigation damage has been caused to around one kilometre of overhead wires. Our engineers have worked through the night to carry out repairs and continue to work on the affected section of railway, but the scale of the problem means no trains will be able to run through this section until midday at least, when a diesel-only service will be able to operate."
Mr Crow said: "We have been raising serious concerns about the shortage of overhead line (OHL) crew and capacity on Britain's railways for a number of years now. We repeated those points only last week when the lines came down at Radlett and now just days later we have another massive OHL failure on our hands. We cannot carry on like this."