It has been announced that two classic episodes of Doctor Who - thought to be missing forever - have been returned to the BBC archives.

Galaxy 4

It has been revealed that episode 3 of the First Doctor story "Galaxy 4" and episode 2 of the Second Doctor story "The Underwater Menace" were purchased by film collector Terry Burnett at a village fete near Southampton in the early 80s. He had been unaware that the canisters contained material missing from the BBC.

It seems that Terry Burnett had no idea the BBC did not have the recordings and it was only when he mentioned them casually in conversation to Ralph Montagu, head of heritage at Radio Times, that their significance was recognised. These latest discoveries are the first complete episodes to have been located since 2004.

Thanks to the kind loan by Terry Burnett, the classic footage was shown at the British Film Institute's annual "Missing Believed Wiped" event at the National Film Theatre in London on Sunday 11th December 2011. Host at the event was Doctor Who writer and actor Mark Gatiss who 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?'.

This find though makes only a modest dent in the number of missing episodes, with now 106 instalments broadcast between 1964 and 1969 still being sought by the BBC.

"Airlock" is the second episode of a four-part story called "Galaxy 4", transmitted in the autumn of 1965. Until its discovery none of the four episodes of this 1965 adventure were known to have survived, although a short extract had been retained.

In this story William Hartnell is accompanied by Peter Purves (who played Steven Taylor), later a presenter on the children's series Blue Peter, and Maureen O'Brien (who played Vicki), now better known as a novelist. The plot involves the desperate attempts by the Drahvins, a race of cloned females, to escape a planet which is about to explode. This story also marks the only appearance in the show of tiny robots known as the Chumblies.

The Underwater Menace

The other re-discovered episode is the second part of "The Underwater Menace", from early 1967, and stars Patrick Troughton, in only his third appearance as The Doctor. The Third part of this story already exists so making this newly found episode the earliest appearance for the Second Doctor that currently exists.

This four-part story sees a mad scientist attempting to restore Atlantis by draining the ocean into the Earth's core. Innes Lloyd, who produced "The Underwater Menace" later admitted 'it did look like something from a "50s American B" movie'.

Research has shown that the returned episodes originated from the ABC channel in Australia and that the copy of "The Underwater Menace" is still missing a few short sections which were removed by the Australian censors upon its original transmission.

It is understood that fresh scans of the missing material have been made by the National Archives of Australia and will be incorporated into the restored episodes ahead of a DVD release.