Christmas railway disruptions

Tis the season to check if the trains are running over the Christmas period, with a lot of lines closed or diverted for engineering works in the London region.
As usual, no trains whatsoever on Christmas Day, and hardly any trains on Boxing Day, and then generally amended timetables for the rest of the week until conventional rail service resumes on Tuesday 4th January.
For travellers to Heathrow Airport, be aware that the London Underground’s Piccadilly line will be suspended between 24th