1869

In 1869, on Christmas Eve, the Gelth attempted to conquer the Earth.

The Ninth Doctor and Rose Tyler arrived on 24 December, 1869, and met Charles Dickens in Cardiff. After discovering the plight of the Gelth, Gwyneth allowed them through a weak point in the Cardiff Rift, but died in doing so. Though dead, she lit a match, trapping the Gelth inside the Rift in an explosion after their intentions were revealed. Gwyneth was later noticed to have shared spatial genetic multiplicity with Gwen Cooper. (TV: The Unquiet Dead, Boom Town, Journey's End)

Captain Jack Harkness, having recently been revived by Rose Tyler as the Bad Wolf following an encounter with the Daleks, accidentally travelled back from 200,100 to 1869 (he had planned to go to the 21st century, when his vortex manipulator malfunctioned. Having become immortal, Jack spent nearly a hundred and forty years on Earth, waiting for a chance to reunite with the Doctor. (TV: The Parting of the Ways, Utopia)

Behind the scenes

It's interesting to note that Jack Harkness was present for the events of The Unquiet Dead, as that story introduced both the Cardiff Rift, (the main focus of the first two seasons of Torchwood, in which Jack's the principal character) as well as Gwyneth, ancestor of Gwen Cooper. (another main character of Torchwood)