Trivia: Torchwood is an anagram for Doctor Who, the show of which this series is a spin-off.
Trivia: The hand preserved in a glass jar in the Torchwood HQ is the severed hand of Doctor Who which he lost in a duel during the Christmas special. The hand features quite prominently in episode 1 but can also be seen in the background in most episodes.
Trivia: Eve Myles, who plays Gwen also plays the maid character Gwyneth in the Doctor Who (season one) episode "The Unquiet Dead."
Answer: He might have requisitioned or stolen it from Torchwood London, or he might have been ready down below once it'd been severed, searching for "the right Doctor" and not knowing that the newly-regenerated Doctor was the one he was looking for.
Captain Defenestrator