Trains have resumed some service on the East Coast Main Line after overhead wire problems caused chaos for travellers.
East Coast said a half-hourly service was now operating from London King's Cross and other services would "progressively resume throughout the day".
The company had initially hoped that a problem with overhead wiring between Stevenage and Hitchin would be sorted by 7am today.
But another incident on the line early this morning closed all four lines through Hitchin, causing mass cancellations and delays.
Services into and out of King's Cross were stopped after the damage on the line that links London with Edinburgh.
It meant that East Coast, Grand Central and First Hull Trains were forced to start and terminate at Peterborough.
First Capital Connect have been running shuttle train services between Letchworth Garden City and Cambridge, Biggleswade and Peterborough, and Welwyn Garden City and London Kings Cross.
Replacement buses have been running between Stevenage and Luton and Hertford North, and between Letchworth and Biggleswade and Welwyn Garden City.
"We apologise to passengers for the continued disruption to East Coast services this morning," East Coast said.
"Trains are now starting to move again through the affected area near Hitchin. A half-hourly East Coast service is now operating from London King's Cross and we expect services to progressively resume throughout the day.
"Earlier this morning, another train operator's service joining the main line at Hitchin was involved in an incident which led to reports of new overhead power line damage, following damage yesterday afternoon.
"Network Rail - which is responsible for track, signals and overhead lines - tell us that further damage to the overhead power lines was found at just before 07.00 this morning.
"In the meantime we have made arrangements for passengers to travel via alternative routes. Road replacement services are operating between Peterborough and Bedford; and we have been operating a shuttle service between Peterborough and Cambridge using a diesel train.
"All ticket restrictions have been lifted and East Coast tickets are being accepted by other operators on alternative routes."
East Coast advised passengers to turn to Twitter for more information about the disruption, using hashtag #Hitchin.
Passengers stuck on their way into London used Twitter to air their frustrations.
@phildoug wrote: "#hitchen all lines 4 lines into London closed on EC train stuck at St Neots, they may turn it round!"
@noelmc66 said: "Travelling on #eastcoast today? Forget it. Peterborough Stn resembling a (well dressed) refugee camp #chaos."
Another, @JRE111S, wrote: "Dear Santa - this year could I have some new overhead cables for the #Hitchin line? some boys on your naughty list seem to have stolen them!"