Just this week the Gatwick Express service from London has announced that due to engineering works it will be closed for much of the period from Christmas to New Year.

In the UK trains do not typically run on the 25th or 26th December, but this year the only option on the 26th to and from Gatwick will be a 90 minute journey:

Southern trains will run every 30 minutes between London Bridge and East Grinstead calling at East Croydon. A frequent connecting bus will run between East Grinstead and Gatwick Airport. This journey will take approximately 90 minutes

On 27 December to 1 January the option is (at least) a slow train:

Southern trains will run every 30 minutes between London Victoria and Gatwick Airport. This journey will take approximately 95 minutes and call additionally at Clapham Junction, Sutton, Dorking, Horsham and Three Bridges.

On 2 January services return to normal on the Gatwick Express.

The explanation provided is as follows:

The revised service will allow Network Rail to undertake vital improvement work at three locations on the network – replacing a major rail junction near Purley (north of Gatwick), upgrading signalling at Victoria and working on a new platform at Gatwick Airport station.