The location of seven currently-officially-missing episodes of Doctor Who has been confirmed by episode hunter Philip Morris, currently leading efforts to recover the missing material. Negotiations are underway to get the missing material returned to the BBC.
Update: Morris has - somewhat confusingly - suggested on Twitter that this interpretation is incorrect, although - on video - he said outright that the locations of these episodes have been identified and he is confident of their eventual return. I suspect based on his comments that the "negotiations are underway" bit is what is under contention, due to his statement elsewhere that his approach is "letting things lie" until the episodes are returned in their own time. So, to be more accurate, the continued existence of seven missing Doctor Who episodes has been confirmed, with the hope that one day they will be returned to the BBC.
The rest of my original report follows:
As was common at the time (from its inception until the 1970s), the BBC used to produce television programmes with no expectation that they would ever be repeated or commercially released. Once aired, it was common for the tapes containing TV shows to be wiped and re-used to save money. Doctor Who was a victim of this process, with 147 episodes junked between 1967 and 1978. These episodes consisted almost entirely of material from the First and Second Doctors (William Hartnell and Patrick Troughton), the first six seasons of the show, aired from 1963 to 1969 and filmed in black-and-white, which was considered even less valuable in the colour era. Some material from the Third Doctor, Jon Pertwee, was also destroyed, but later recovered via black-and-white copies that were digitally re-colourised.
The advent of the home video format in the late 1970s and intervention from fans made the BBC change its mind quite rapidly and almost as soon as it stopped the purge of its archives in 1978 it began trying to reclaim the lost material. In some cases BBC engineers had saved episodes and kept them safely at home, or sold them to private collectors. The most valuable resource, however, was the BBC's foreign sales department. Since Doctor Who began in 1963, it had been sold widely abroad, particularly in the Commonwealth, and in many cases those countries had hung onto their copies of old episodes. Between 1978 and 2013, 50 missing episodes of Doctor Who were recovered from these sources and returned to the archives.
This has left 97 episodes - one eighth of the total number of episodes of the entire series - officially missing. 26 serials are affected, with 10 serials completely missing altogether.
The last time missing material was returned to the archive was in 2013, when Philip Morris recovered nine missing episodes from a TV station in Nigeria. These episodes constituted all of the missing material from the serial The Enemy of the World and four of the five missing episodes from the immediately succeeding serial, The Web of Fear. In the case of The Web of Fear, it was revealed that the remaining missing episode (the third) had also been identified, but had been removed from the station by persons unknown before the rest of the serial was sent back to the UK.
Morris has since confirmed that the identity of the people who took the episode has become known and very delicate negotiations undertaken to hopefully return the episode.
Five additional episodes were recovered by Doctor Who fan Ian Levine the same year from Taiwan, but these were additional copies of episodes already in the archives. Nevertheless, the discovery promoted renewed interest in Taiwan as a location of interest to episode hunters, although some questions were raised about the find.
During the Time Space Visualiser 2 online event earlier this year, Morris confirmed that "at least" six more episodes currently officially listed as missing have been identified in the hands of private collectors. The principle block to them being secured is not money, but rather the fear of the collectors that fans might learn their identities and berate or harass them (as has happened, to some degree, in the past, even to Morris himself despite his success in recovering episodes from overseas). Even more delicate negotiations to secure the anonymity of these collectors are required before they can be returned to the BBC archives.
The hunt for the missing episodes has gained some urgency in recent years. 1960s BBC film stock is fairly durable, but after being left in tin cans in dusty back shelves of basements in places like Australia, Singapore, Hong Kong and Nigeria, it's possible that some old stock will have become unusable: some reports have surfaced of promising leads ending only in old warped cans filled with unidentifiable goop that may have once been film stock. It is also already known that at least one TV station in Sierra Leone had a very large stock of the missing episodes (almost all of them, according to some records) before being levelled to the ground in the civil war in that country in the late 1990s. Time is not on the hunters' side here, but it is good to know at least some more missing episodes from the show have survived.