Not every line is your friend on the 25th. The Waterloo & City line, which is basically a short sprint for bankers, doesn’t run at all. It’s too short to care about Christmas.
The Night Tube, those lovely late-night services on the Central, Victoria, and Jubilee lines? Forget about it. They are cancelled. The entire network becomes a daytime-only operation.
And the Overground? It’s a mixed bag. Some parts run, some don’t. It’s like that distant cousin who might show up to the party, but you can’t rely on them. Always, always check the TfL website before you leave.