East Coast mainline has said it is operating a "near normal" train timetable following severe disruption to services on Tuesday.
All services between Cambridgeshire and London King's Cross station were cancelled because of a problem with overhead cables.
But East Coast warned that some of Wednesday's services had been cancelled and journeys could still take longer.
Passengers have been advised to check travel information before setting out.
'Home for Christmas'
Managing director Karen Boswell apologised for any inconvenience.
"We appreciate that many people are travelling home for Christmas over the next few days and our staff are working as hard as possible to ensure our passengers arrive at their final destination with minimal disruption."
On Tuesday overhead cables failed in the Huntingdon area, near Peterborough.
All trains from both north and south were stopped at Peterborough.
Hundreds of passengers were stuck on six trains, with some having to be taken from the carriages using ladders.