The BBC lists 108 episodes of Doctor Who from the 1960s as officially "missing" from its archive. That's because the original videotapes were either erased or destroyed by the BBC in the 1970s, to make shelf space for newer programming. A catastrophe for fans. But Doctor Who - as fans of the show will know - is luckier than most.

The programme has always had a very loyal, and often talented, fanbase. It was its dedicated fans who in the 1960s weren't hiding behind the sofa, but holding microphones up to their televisions week after week, that meant that all of the missing 108 instalments still exist as audio recordings; and it has been today's fans who have, over the past few years, been working on bringing these "lost" recordings back to life through animation.

In 2006, James Goss, a producer working with the BBC's interactive arm, took two audio-only episodes from the 1968 story The Invasion to the animation studios Cosgrove Hall to produce an all-new black and white animation, lip-synced to the original audio - in effect, bringing back to life two lost gems from the BBC archive. The episodes were released on DVD and went on to become one of BBC DVD's most successful Doctor Who releases.

Invasion of the fans

However, since The Invasion project, no further episodes have been given the animation treatment by the BBC.

Dan Hall, commissioning editor for the Doctor Who DVD range, says: "Unfortunately these things have to be paid for, and animations are very expensive. The Invasion ... was a co-venture that was majority-funded by the BBC, and they've decided not to invest in them any further.

"I would love to do another animation. It's just a matter of finding a way that it can be done affordably. It's nowhere near affordable, and it's not one of those things where you can ... just make a smaller profit on it."

Now dedicated fans from around the globe have entered the scene to work on their own animations of lost stories, entirely separate from the BBC.

Garrett Gilchrist is a director and artist based in the US, where he has produced a series of low-budget movies. For the past eight months he has been working on an ambitious project to restore to life an episode of the lost 1967 Patrick Troughton epic, Evil of the Daleks.

"The Invasion DVD was such a gift to fans, such a wonderful project," he says. "The first thought in everyone's mind was, 'So, when are you animating the rest of them, then?' "

Working from a basis of hand-drawn 2D animation, Gilchrist has created a series of artworks of all the main characters needed and has worked them into the animation.

"I use a very painstaking method, working very closely from photos," he says. "Everything has to match the original photo perfectly. I wanted my animations to look like a painting come to life - looking just like the original actors, only with cartoon lines around them."

Gilchrist's efforts, and those of others, benefit from the cooperation of an online community of fans; already Gilchrist's work, on what he calls the WhoSprites project, is nearing the completion of an entire episode.

But while the work of Gilchrist and that of The Invasion DVD relies on traditional 2D animation, many more projects are working in the more complex field of 3D CGI. Much of this work is concentrated around the loose collective of the WHO3D group.

Established in the 1990s with the bold aim of producing professional-quality CGI animations from early Doctor Who audiotapes, the project has produced some surprisingly accomplished products.

"Done in the right way, CGI could breathe life into 60s Who in a way that we may never otherwise see again," says Marc Taylor, a member of the group. He is working on a large-scale CGI realisation of Patrick Troughton's first story as the Doctor, the six-part Power of the Daleks, made in 1966.

"We are just over six months in," says Aaron Climas, an Australian-based animator working on the project. "It is a little complicated, but animation isn't just something you sit down and do, in the same way you don't build a house by getting some wood and start nailing."

Taylor agrees: "You can spend literally hours trying to figure out the sets and how everything is laid out. There are many variables involved. Not least, how good your computer is. I can't tell you the frustration that you get from waiting ages on a slow machine ... A complex scene, in the console room, is a good 30 minutes to get a render back - because there's a lot of glass refraction and lighting."

In spite of the time involved in creating these episodes, however, attention to detail is still held to be paramount. "They have to match the original episodes as closely as possible, and feel like the 60s Doctor Who, not updated," says Gilchrist. "Just recreated with new technology. Recreated, not updated."

Of course, all of the many projects in production are independently produced, and although many of the artists involved have actually worked in some capacity for the BBC's Doctor Who ranges (on cover illustrations or DVD features, for example), the whole endeavour is an entirely amateur one, albeit often with professional flair. And yet, with no further official animations planned by the BBC, it is easy to see why those involved have such zeal for their work.

Recipe for success?

"The audio for these productions exists, with many, many images from filming and camera scripts. All kinds of materials are sitting there waiting like a set of cooking ingredients," Climas says.

Gilchrist agrees: "It's up to us now to take the superglue and put these broken episodes back together. Perhaps this is the sort of thing that should ideally be done by a fan - a fan with talent, but a fan nevertheless."

Whether any of the productions worked on will bring about a professional commission is yet to be seen, but BBC DVD is open to suggestions and, even if the money is lacking, the goodwill is still there.

"Certainly, I've been offered lots of alternatives," Hall says. "I don't think any of them have been up to the quality that I think the market deserves ... but it's an idea I'm always keeping an eye open for. When people write to me and say 'Can we do a test?' I will gladly look at it and schedules are always movable. You can always make room for things, if something good crops up."