RAIL bosses say a normal train service may return tomorrow – but warned commuters could face further delays.
Passengers in Huntingdon and St Neots have been affected today, with many services heading towards London cancelled.
It follows a power line failure yesterday.
A spokesman from First Capital Connect (FCC) said work would be carried out overnight - but admitted getting the service back on track would be a challenge, because trains and crews may need to be shifted.
He said: "Network Rail say that they anticipate finishing the work early tomorrow morning.
"If they are completely repaired, that line will be back open.
"Whether we're able to run a normal service depends on where we've got trains and where we've got crews."
A revised timetable for this evening has been drawn up and trains are leaving King's Cross to Peterborough twice an hour - at six and 36 minutes past the hour.
Trains travelling from Peterborough to King's Cross depart at 16 and 46 minutes past the hour.