The timetable introduction will be phased, with the last stage introduced after the holiday period on Tuesday, January 4 2022. Until January 4 there will be improvements and changes on some routes but also temporary service reductions on others. This will support significant engineering works over the Christmas and New Year period, and ensure planned services are as reliable as possible with the ongoing impact of Covid-19 on GTR’s operation. It will also reflect changes to services during bank holidays and the Christmas and New Year week. It’s important for passengers to check before they travel in this period. Gatwick Express also returns on Monday, December 13, to support the recovery of Gatwick Airport and the South East economy. Services were suspended on March 30 2020 as the pandemic took hold and passenger numbers at the airport tumbled. Passengers at the airport are now returning in greater numbers. Gatwick Express, however, will also be affected by engineering work until January 4. GTR interim chief operating officer Angie Doll said: "We’re changing our train times in phases from December 12 to support engineering work and ensure services are as reliable as possible given the ongoing impact of Covid-19. "We do strongly urge our customers, including those travelling to see friends and family over the festive period, to check before leaving home using live travel updates on our websites and at National Rail Enquiries where they can also sign-up for alerts." "We’re pleased to reinstate our seven-day-a-week non-stop Gatwick Express service. Gatwick Airport plays a vital part in driving economic growth in the South East and we’re proud to support its recovery." Passengers are also reminded that, from today, they must wear face coverings across the railway unless exempt. The Christmas and New Year timetables from December 25 to January 3 are already available to view in online journey planners such as www.nationalrail.co.uk. Train times for the two earlier phases in the run-up to Christmas, on Southern and Thameslink, are being updated, with reduced services in some cases. Timetables will be available as follows: Journeys between Sunday, December 12 and Saturday, December 18, available in online journey planners from Monday, December 6. Journeys between Sunday, December 19 and Friday, December 24, available in online journey planners from Monday, December 13. A summary of changes is available online at southernrailway.com and thameslinkrailway.com.