21 December

In the southern hemisphere on Earth, 21 December was also known as Midsummer's Eve. (PROSE: Iceberg) In the northern hemisphere, it was instead the winter solstice. (PROSE: The Left-Handed Hummingbird)

In 2010 was also the date of an unknown Torchwood Three operation. The date was in both Captain Jack Harkness' and Gwen Cooper's CIA files, detailing the figures of a "case" numbered "00938478766-04". The precise nature of this case remains unknown. (TV: The New World)

In 1981, the Hecate Cult intended to sacrifice Brendan Richards in Moreton Harwood. However, he was rescued by Sarah Jane Smith and K9 Mark III before this could happen. (TV: A Girl's Best Friend)