The Husbands of River Song (in-universe)

The 2015 Christmas special of Doctor Who was broadcast on Christmas Day. It promised to be "a humongous feast of festive entertainment", and featured the return of River Song.

In a letter to the readers of an issue of Doctor Who Adventures, the Twelfth Doctor told them that, now that December was here, there was only a short amount of time to wait for the special. (PROSE: Dear Readers)