Holidaymakers are facing travel chaos over the Christmas period as rail links to Britain's two biggest airports are severed.
Gatwick Express trains will stop running for 10 days due to engineering works, with the last service of the year leaving Victoria station at 9.15pm on Christmas Eve and not restarting until January 4.
At Heathrow, the normal one day closure on Christmas Day will be extended by three days due to Crossrail works. Neither Heathrow Express nor Heathrow Connect trains will run from London Paddington station during the period.
Train operator Great Western Railway said services will be disrupted "as part of a large programme of engineering in the Thames Valley needed for the launch of Crossrail in 2019".
Stephen Joseph, director of the Campaign for Better Transport, said: "These engineering works will of course cause huge problems for travellers and I suspect the decision has been taken to inconvenience airline passengers rather than inconvenience commuters.
"What these closures highlight, however, is the lack of surface transport options to both Heathrow and Gatwick, which is something the Government is still failing to address in its plans for airport expansion."
A Heathrow airport spokesman said: "Due to essential Crossrail improvement works being carried out by Network Rail, Heathrow Express services will not run from Friday 25th to Monday 28th December 2015.
"The Piccadilly Line and additional bus and coach services will be operating. Passengers are advised to leave extra time when travelling to the airport."