- You may be looking for the Seventh Doctor short story.
The Doctor has been taking Leela to experience several different Christmases, but Leela has had enough of Christmas. When the TARDIS dematerialises, the Doctor is apologetic — they have landed on Gloricious in 2172, on Christmas.
As the doors open, a man runs into the TARDIS. He is on the run from security. His name is Kamble, and he tells the Doctor and Leela that the colony had undergone climate change. A trio of aliens arrived and are using their mental powers to maintain the right climate, but in return they have declared that every day is Christmas, and as their presents they demand human sacrifices. Kamble, one of the "presents", escaped.
The Doctor confronts the three "Kings", who have made their lair inside a giant Christmas tree. They are not afraid of him and knock him unconscious.
When the Doctor wakes, he is dressed as Santa Claus and tied to the top of the tree. Below, Leela and Kamble are being brought inside the tree to be the Kings' presents. The Doctor, using his sonic screwdriver, determines that the Christmas ornaments are actually power sources that are keeping the climate under control — the aliens are not using any mental powers at all.
The Doctor shouts his findings down to Security Officer Grey below. Other colonists gather, and they acquire makeshift weapons. They enter the tree and kill the aliens, freeing Leela and Kamble.
The Doctor, upset that the colonists killed their oppressors, leaves with Leela.
- The Doctor took Leela to Austria to see the first performance of "Silent Night".
- Leela doesn't want to see any more sherry or mistletoe.
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