I do my best. But as has been pointed out, there
is evidence that the episodes take place in the years of broadcast-- the
Harry Potter reference in "The Shakespeare Code", background signage in some episodes, &c.
Reasoning that
The Wormhole and
Brandon Moody haven't pointed out yet:
"School Reunion" has to occurs between "The Christmas Invasion" and "Rise of the Cybermen".
"Army of Ghosts" and "Doomsday" have to occur in June at the earliest since the ghosts appeared two months prior but there was no sign of them in "Love & Monsters".
"Everything Changes" seems to be a few months after "Doomsday"; "They Keep Killing Suzie" is stated to be three months after that so the intervening episodes must distribute between them. "Out of Time" is stated to be around Christmas; "Combat" is shortly after it; and "Captain Jack Harkness" and "End of Days" not much later. (A missing poster on the
Torchwood website says that Jack disappears in February.)
All of Season Three's present-day episodes occur in the same week, eighteen months after "the downfall of Harriet Jones", and also pretty close to "End of Days" (when in present-day London, the Doctor says the last place the TARDIS landed, present-day Cardiff, was "right here, right now"). June is a good, if rough, placement.
The exception in Season Three is of course "Blink"-- Kathy Nightingale says she comes from 2007. The epilogue occurs a year later, but presumably before the Week of Saxon.
Also, John Smith says in "Human Nature" that the Family attacked them in 2007; Martha's MySpace says they had popped back to see the 2007 Eurovision when this happened, placing that bit in May.
"Invasion of the Bane" should occur
at least eighteen months after "School Reunion" since K-9's been in the black hole that long... but "Turn Left" means that it also has to occur before "Smith and Jones". "Revenge of the Slitheen" is set at the start of a school term, and references to "months" passing here and there meant that I distributed the rest of the season out to December. I had more specific reasons when I watched the episodes, but I don't remember them anymore.
"To the Last Man" has to be less than a year after "Everything Changes" because Gwen has never met Tommy before. I read a decently compelling argument on the OG forums that "Something Borrowed" was set in December; the rest of
Torchwood Series Three is pretty arbitrarily distributed over the intervening time. "Adrift" says that the sighting of Jack next to the disappearing boy happened seven months prior, so the episode has to happen in February 2009 or later so that Jack will actually be there. And then "Fragments" and "Exit Wounds" have to occur 21 months after "Doomsday" because of the Ianto flashback.
I think that pretty much covers it!
