The missing episodes weren't resurrected via trip back in time in the Doctor's TARDIS: they came from the private collection of former TV engineer Terry Burnett, who didn't realise he was sitting on a hidden treasure till he met up with Doctor Who fan Ralph Montagu. It's believed the episodes originated from our ABC (Radio Times has the full story).
The episodes, titled 'Galaxy — part 4' (featuring the first actor to play the Doctor, William Hartnell) and 'The Underwater Menace - part 2' (featuring the second Doctor, Patrick Troughton), were unveiled at a British Film Institute's event in London on December 11.
In 'Galaxy', "various factions vie to leave a barren world before it explodes — a race of bad girls called Drahvins, cute domed Chumbley robots and the benign warthog-like Rills", while 'Underwater Menace', "is arguably the more intriguing find... [because] it’s actually now the earliest surviving episode to feature the second Doctor".
The old tapes aren't in perfect condition: they're covered with "a bit of muck and dirt" (which can be fixed) and a "tramsline scratch", a vertical line left by someone who didn't maintain their projector (which probably can't be fixed). One of the episodes is also missing a crucial 27 seconds at its cliffhanger.
Until the late '70s it was BBC policy to re-use tapes, overwriting their content instead of archiving it...
which seems bafflingly stupid in hindsight. There's still more than 100 lost episodes of Doctor Who — but who knows how many are sitting out there somewhere, waiting to be found?
The new Doctor Who Christmas special 'The Doctor, the Widow and the Wardrobe' (starring the 11th Doctor, played by Matt Smith), will air on ABC1 on Boxing Day at 7.30pm.