Doctor Who: 10 Things You Didn't Know About UNIT
6. The Classic Serial That Broke UNIT's Timeline
Nobody knows when the UNIT stories take place, and nobody ever has.
The events of The Invasion and the Jon Pertwee era were supposed to be taking place in the near future, and Battlefield is set in the 1990s, which sort of sits into this timeline – if it weren't for the fact that Mawdryn Undead exists.
Originally intended to feature an older Ian Chesterton, this serial was rewritten to feature the Brigadier instead. The only problem with this was that nobody thought to change the time period in which the story was set, which is why the Brigadier says he retired from UNIT at some point prior to 1977, a few years before the UNIT era is said to start!
Chris Chibnall finally tried to make sense of this in Flux by suggesting that the Grand Serpent had been messing around with time, which is why the UNIT timeline is all messed up. It was a noble effort, but fans didn't seem to notice that this was what he was doing.
Whenever the UNIT stories are actually set, we can all rest easy that their Season 1 episodes will all definitely, 100% take place in 2024.
Probably.