Board Thread:The Reference Desk/@comment-60605-20140919101627/@comment-188432-20170601004757

There are no definitive answers possible, but Bwburke94 has pointed out some prominent fan theories. Basically SJA timing, at least for some of the run, is impacted by Rose's "one year later" moment early in series one of Doctor Who. Sarah Jane, after all, exists with Rose's narrative time frame because they crossed paths in School Reunion, and because K9 Mark IV arises from that story and later appears in SJA. So SJA can't happen before School Reunion, tying Sarah Jane to Rose.

But SJA timing gets murkier the further you get into the programme's run -- and therefore the further you get into the runs of Torchwood and Doctor Who itself.

This kinda thing is why we ruled long ago that timeline dating efforts belong in the Theory namespace. They shouldn't appear on story pages or be declarative statements on in-universe pages. In almost every case, it doesn't matter to your enjoyment of SJA stories what year they take place in, save perhaps their proximity to other SJA stories.