Doctor Who fans were treated to an early Christmas special after the BBC announced it had found two previously missing episodes from the 1960s.
The broadcaster announced to fans last night that the two episodes had been uncovered at the Missing Believed Wiped event at the BFI in London before it was released in a series of messages on Twitter.
Galaxy Four, part three, was first broadcast in 1965 while The Underwater Menace part two, was aired in 1967 and both had been thought to be lost.
The returned episodes originated from the ABC Channel in Australia.
There are believed to be more than 100 original episodes missing because the BBC did not start routinely archiving shows until 1978.
The official Doctor Who Twitter account tweeted a cryptic clue last night: "Christmas has come early for Doctor Who fans. Expect us to tweet some very – no REALLY exciting news in just a couple of hours' time ..."
Later, the account revealed: "Two previously missing episodes of 1960s Doctor Who returned to BBC. Galaxy Four pt 3 & The Underwater Menace pt 2. Details soon."
The BBC then released images from the rediscovered original footage.
Doctor Who writer and actor Mark Gatiss said: "Christmas has come early for Doctor Who fans everywhere. It's always wonderful when a missing episode turns up but it's been years since the last one so to have two is just brilliant.
"Add to that a proper bit of action from the legendary Chumblies (and the horrifying Rills!) plus the utterly mesmeric Patrick Troughton on great form. Well, what more could we all ask for?"
Clips from the missing episodes show William Hartnell starring in Galaxy Four with Patrick Troughton in The Underwater Menace.
A commercial release is expected to be announced in 2012.