The Department is a secret organisation charged with the Occult Defense of the Realm. The realm in question is what was once the British Empire, so it really can be active anywhere in the world especially as global threats threaten the UK as much as they do anywhere else.
Department Y 
Whoa..your banner is psychedelic.
Yes, yes it is. It’s modeled on the psychoactive ID cards the Department uses but it’s completely harmless. So I’m told.
i just read the first post and i’m already feeling dragged into a new series of ‘Torchwood’ i wasn’t aware of – or another of Charlie Stross’ ‘laundry’ novels. i’m hooked.