Christmas commuters will face delays as work continues on the West Coast Main Line.
The route will be closed at Milton Keynes meaning Birmingham passengers will have an hour added to journeys to London.
Virgin Trains will run services to London Euston but this will be hourly from Birmingham International instead of New Street on Saturday December 27 and Sunday December 28.
Jim Rowe, from Virgin Trains, said: “Network Rail will continue to work on part of the track at Milton Keynes, which means we can’t run our trains on the West Coast Main Line via the direct route.This will add about an hour to train journeys.”
Network Rail is set to complete an £8 billion programme which will improve the rail network and allow an extra 350 trains.