OK, this is something I don't recall picking up on back in the PBS days when I first discovered the Baker stories. I had always assumed that when the Doctor was back on Earth in the 'present' it was reflective of the time the show was made; in other words, with Tom as the Doctor, the show's present was in the mid-70s.
But while watching The Pyramids of Mars last night on DVD, Sarah Jane states not once, but several times that she's from 1980, five years ahead of when PoM was aired. So does that mean that the original first season Hartnell stories were set in 1968? When was the first time that the show's present was established?
This really threw me a curve, as I recall that in nuWho, the Doctor made references to meeting Rose in 2005, which corresponded to real-time.
Just curious. It's probably one of those things we're not supposed to think about too hard.