A double whammy of good news for Classic Doctor Who fans.
William Hartnell Episode Airlock Found!
Airlock is the third part of the 1965 story Galaxy Four
This is the only complete episode of this story known to exist. Only Stills and some clips exist of the rest of the story.
Patrick Troughton Episode Found!
This is the second episode of the 1967 story? The Underwater Menace
Episode 2 joins episode 3 as complete episodes from this story.
Sources and further reading: