Below are just some of these rumors. I have compiled them from various different sources so the information available on each may vary.
Marco Polo
All: For many years it was suggested that the collector who returned Episode 6, and later a better quality copy of Episode 3, did in fact have the entire story, and would not return it to the BBC because he didn't think the prints would be safe there. The story, which makes no sense, has since been dismissed.
Episodes 4 & 5: Rumors are still circulating today as to whether parts 4 and 5 of The Reign of Terror still survive in Cyprus since it is where episodes 1,2,3,4 and 6 were discovered in 1984. It is unlikely, however, since the vault that episodes 4 and 5 were said to be stored in was destroyed, along with all its contents, in a shell attack during the illegal Turkish invasion of Cyprus in 1974.
Episode 5: Supposedly in the possesion of an American fan.
Episode 2: Is in the posession of a fan.
Episode 4: Blue Peter, to celebrate Doctor Who's Tenth Anniversary,
screened a feature which used a number of clips from various episodes, including The Daleks Masterplan episode 4 and The Tenth Planet episode 4. After the clips were extracted from the episodes they went missing from the Blue Peter Production Office. There are a great number of rumours concerning the whereabouts of this episode. Over the years, the episode has variously been rumoured to be in the hands of an oil rig worker, a chap in Leeds, and a consortium of ten fans who paid £50 each for it in the mid-eighties. The one common theme running through each is a distinct lack of evidence or proof to back up the claims.
Episode 4: A film can containing an episode of Coronation Street which had "Tenth Planet 4" written on it in marker pen was apparantly shown at a convention as a practical joke.
Episode 4: A BBC employee reportedly "borrowed" this episode from the archives. The BBC was said to have known who he was and was supposed to have attempted a recovery in early 1993. However, the "copy" that was returned to the BBC was reported as being a blank. The employee was said to have sold the actual episode to an unnamed collector for £5000.
All: It has been reported in a number of places that the people who were burning the BBC
Enterprise 16mm telerecordings saved several Episodes, including some which are still
missing to this day. One of the stories that was said to have been saved was Power of the Daleks.
All: For years it had been stated as "fact" in many places that
The Power of the Daleks was screened in Ghana in 1986. The Episodes could not be recovered
however, as the Ghanaian archives burnt down a few years later. The truth of the matter is
that it wasn't shown in Ghana in 1986 and that they didn't even buy the story. This rumour would
appear to have started around 1991 at the Tavern in London, and spread out from there via
DWB. There is also no trace of a mention of the Ghanian TV archives
burning down anywhere outside of articles on missing Doctor Who.
Episode 1: This episode is said to exist in the UK. The asking
price is said to be £15500.
Episode 2: In his May 1994 article, "Missing Without Trace," Paul
Lee reported that a print of this episode was said to have been in the possession of an oil-rig worker in late 1992. He reportedly paid £5000 for it a number of years before. Paul said he knew the worker's name but did not want to reveal it for fear of jeopardizing future negotiations. However, as of 1999, this episode remains missing from the BBC archives.
Episode 2: Is rumored to be in the hands of an English collector, who will not return it nor reveal its existence. However, the private collector was said to have relented and to have shown the episode to a few people.
Episode 3: It was reported early in 2001 that episode 3 had been located and sent to the British Film Institute. It hadn't.
Episode 4: An Australian fan once claimed to have this Episode and used clips from it to obtain rare archive material. It later transpired that all he had was a small number of clips taken from an Australian documentary called Perspectives; C for Computer, and nothing else.
Episode 4: Was supposed to have been returned by fan Nick Manganas.
It turned out that the post on a message board proclaiming this was written by an impostor, and the real Nick Manganas denied all knowledge, as he had nothing to do with it.
All: In the mid-nineties, a fan claimed that a friend had all four episodes. He didn't.
Episodes 2 & 4: Said to be in the posession of a scottish film collector.
All: It has been reported in a number of places that the people who were burning the BBC Enterprise 16mm telerecordings saved several Episodes, including some which are still missing to this day. The Moonbase was one of the stories that was said to have been saved.
Episode 3: Is said to be in the collection of an American fan
All: It was suggested that after the Hong Kong find, a fan supplied the BBC with a poor quality print of the story. They didn't.
All: One tale goes that during the Seventies, Anthony Coburn did some uncredited script editing on Doctor Who. For contractual reasons, he could not be paid for this work and so as an alternative to payment, he asked if his son could be given a copy of a Doctor Who
adventure, and was given The Web of Fear. A slight variation on this is that he did a script
re-write as a favour for the producer, and asked for the copy of Web as payment, rather than cash.
This then passed on to his son when he died, who is hoarding it, and refusing to answer questions on it.
All: Episode one was shown at a convention which reportedly carried on to show the beginning of
episode 2 before being quickly turned off. It turned out that a mock up had been made using the footage from
episode 1 as the re-cap.
Episodes 2-6: It has been reported that Ian Levine used his colour clip of The Mind of Evil
as bargaining material to get these Episodes from an American collector called Bruce Mai,
who had placed an advert in a 1988 edition of a magazine called "Movie Collectors World".
However, as time progressed it became apparent that he did not have the Episodes himself,
and that he was acting as the middleman for a UK collector who he did not name. The
Episodes never turned up.
Episodes 1 & 2: A person from Blackpool (who would become known as "The Blackpool Hoaxer")once claimed to have Fury From the Deep episodes 1 and 2. Ian Levine got in contact with this person and offered his colour clip from Mind of Evil 6 in exchange for the episodes. However, it soon became apparent that this person did not possess these episodes, and in fact had nothing. "The Blackpool Hoaxer" has been responsible for a number of similar pranks over the years.
Episode 6: A scan of the label from the film can of off this episode was posted on a number of message boards with claims that it existed. It didn't. What happened was that back when The Ice Warriors episodes were found, a film can that seemed to be this episode was also found. Inside the can was something completely different. The scan was of the label from this can.
All: It has been reported in a number of places that the people who were burning the BBC Enterprise 16mm telerecordings saved several Episodes, including some which are still missing to this day. One of the stories rumored to have been saved was The Invasion.
Episodes 1 & 4: There is a long standing tale that the two Missing Episodes from The Invasion were sent back to the BBC, but somehow got lost in transit. This rumor is sustained by the early design of the front cover of the video saying something like "Complete at last, with an introduction by Nicholas Courtney", which was swiftly changed to the wording that appeared on the actual release (except in Australia).
Episode 1: An overseas collector has it.