Rail passengers hoping to travel between Norwich and London will face major disruption this Christmas.
No trains will run in or out of London Liverpool Street station from the end of services on Christmas Eve until January 3.
Greater Anglia will also cease all services on Christmas Day and Boxing Day.
This means New Year's Eve revellers heading to the capital will face longer journey times due to switching to rail replacement buses.
Network Rail's route director for Anglia, Ellie Burrows, said the planned works are "critical" for upgrading and maintaining the railway ahead of the year.
"I hope passengers can understand the need for the upgrades and I’d like to reassure them that we’ll be getting a huge amount done while trains aren’t running," she said.
The Liverpool Street work will affect Greater Anglia mainline services from December 27 up to and including January 2.
Rail replacement buses will run from Ingatestone to Newbury Park.
Jamie Burles, Greater Anglia managing director, said: “We appreciate that this work is inconvenient for passengers, but it is vital for the long-term reliability of our busy network.
“We will make sure that our customers can all complete their journeys, even if part of it is by bus.”
Passengers are asked to check with train operators before they travel.
The news comes ahead of "severe" disruption this Saturday (November 26) due to a train drivers' strike organised by Aslef, the train drivers' union.
Services on main routes to London will be heavily reduced and there will be no trains at all on many Greater Anglia lines.
Jamie Burles, Greater Anglia managing director said: “We’re very sorry that once again we must advise people to avoid travelling on our trains, but with our drivers on strike we have no other option.
“We know people will have been planning to go Christmas shopping, visit the Christmas lights in London, go to shows and events or watch FA Cup matches on Saturday, November 26, and that now they will be disappointed.
“We will continue as an industry to carry on talking to ASLEF and other rail unions to try to resolve these disputes, to bring an end to these very disruptive strikes.”
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