The TARDIS returns Tegan to Heathrow Airport: Tall trees, peaceful, clear skies, thriving vegetation and a touch of sulfur in the air. Obviously the TARDIS is a little out of date (about three hundred years or so), but upon looking around the Doctor finds there's more amiss than his navigational controls, all arising after a recent comet crash that was not on Earth's schedule.
Did You Know?
You call three hundred years a small error?
The Fifth Doctor
It's probably due to nothing more than a temperamental cellanoid on the lateral balance cones.