Doctor Who wasn't meant to last 50 years.

It wasn't even meant to last five months. It was created in 1963 by the Australian producer Sydney Newman, but expectations were low and most people at the BBC, including the cast, believed it would run for a few weeks at most.

And then the Daleks showed up and suddenly Doctor Who became an addiction. The show has had its ups (Tom Baker, David Tennant) and downs (it was cancelled in 1989 before being brought back in 2005), but it has always been part of the British cultural consciousness and next week reaches that 50th anniversary no-one imagined it would ever see.

Ahead of the party - the anniversary episode will be shown on Saturday - we have asked the show's actors, writers and fans from across the 50 years to remember some of their favourite moments and help explain why Doctor Who has been with us all this time.

Frazer Hines (played Jamie, companion to The Doctor)

"When I think of Doctor Who, I think of Patrick Troughton, the second Doctor. Working with him were the happiest years of my career - he was a lovely man, and we gelled straight away. As The Doctor, he could make you laugh and then run round the corner and suddenly make you frightened, or vice versa.

"One of the best of my stories was The Web Of Fear, in which the Yeti invade the London Underground. It did that thing that Doctor Who does well, of putting something creepy into something ordinary, and it was claustrophobic.

"My character, Jamie McCrimmon, worked because he could ask all the questions that the kids would ask their dads. The Scottish accent came from my mother, who came from Port Glasgow. I spent all my early summer holidays at my grandmother's house there, and every Sunday we'd either go doon the watter or go to the Buchanan Arms for Sunday lunch.

"I'm slightly disappointed with the BBC over the 50th anniversary. I thought they would have pushed the boat out and shown a William Hartnell story in January, a Troughton story in February and so on. The BBC should have shown it on a Saturday and said to everyone, 'This is how it really was!'"

Rona Munro (playwright and writer of Doctor Who story Survival)

"I have always loved Doctor Who and I'm old enough to remember seeing the first episode at home in Aberdeen. In our family, we had what we called 'the Doctor Who cushion' which is where I would bury my face at the scary bits. I was three and watched it with my parents, and it did get a family audience right from the beginning. It made parents feel comfortable about letting their children look at the bogeyman. It was an aspiration that the show had from the beginning and is still managing to pull off today.

"The story I wrote was broadcast in 1989, and what people say to me is that it was the first to put a woman at the centre of the story in what was until then a boys' show. At the time, I was just doing what I did. Doctor Who was ahead of the game. The beauty of science fiction when it's done well is that you can introduce ideas that are ahead of their time as far as conservative culture is concerned.

"When I did my story, the BBC quite blatantly did not want to keep putting money into Doctor Who and it was only a very loyal fanbase that was forcing them to keep it on the air.

"It's one of these things that's bandied about as absolute fact and therefore everyone believes it to be true: that loyal Doctor Who fans are a bunch of anorak-wearing geeks with unwashed hair and low social skills. They exist, but they do not represent the majority. It was able to be revived by Russell T Davies in such splendid form in 2005 because he was a fan, and hardly in that category."

Tom Baker (The FOURTH Doctor)

"Doctor Who? It's that universal thing, isn't it? This amazement. Suddenly a box appears, and a door opens, and a fellow comes out and says, 'Hello'. And then he can take you somewhere. The only problem was I began after a while to become so proprietorial about the role, so I thought I'd better give someone else a go."

Kate O'Mara (playED the Doctor's enemy, The Rani)

"Doctor Who is a cult, an institution. The part of The Rani was written for me so it was written to my strengths, which was very satisfying. She's totally ruthless and hubristic, a Time Lord who's queen of some extraordinary planet but she wants to be queen of everywhere and dominate the entire proceedings. You have to believe what you're doing when you're doing Doctor Who. It is never parody.

"It is also educational. The first one I did was set in the Industrial Revolution, and you had all of that background. There I was, dressed up in 18th-century peasant gear and then I start turning people into trees. I always believe these things totally when I'm doing them, and that's the way to go.

"Then there's the morality of Doctor Who. The show always fulfils people's expectations and good triumphs over evil. It has to. An unhappy ending is breaking the rules. I hardly dare watch the news these days - Doctor Who provides comfort."

Stephen Greenhorn (writer of David Tennant-ERA stories The Lazarus Experiment and The Doctor's Daughter)

"Working on Doctor Who throws up dozens of moments to cherish. Even production meetings could be memorable. Auditioning six different types of clockwork mouse for a role in The Doctor's Daughter was a surreal highlight.

"In truth though, the single most exciting moment of my time on the show was an intensely private affair: the simple, unrepeatable thrill of starting a script by typing in the words, 'INT. TARDIS.' Nothing beats that."

Ryan Hendrick (actor, filmmaker and fan)

"Doctor Who was a creative inspiration that drove me from an early age. I'm 29 years old and was introduced to it when I was seven in the early 1990s. The one that really caught me was The Caves Of Androzani with Peter Davison as The Doctor. It terrified me and gave me nightmares. That was followed by Revelation Of The Daleks with Colin Baker, which really got my inspiration going. It was such a visually interesting show and, from that moment, I started writing my own scripts.

"It was the spirit of adventure that comes with the character that got me - he's very heroic but also very intelligent. And, apart from regeneration, he has no superhuman qualities. He also has an appeal for boys who are different and I was definitely the different one at school.

"Doctor Who also has a long tradition of inspiring its fans, including Peter Capaldi, the new Doctor, who was a fan when he was growing up in Scotland. There are many people in the industry who were Doctor Who fans, and that was the creative force that drove them into it."

Peter Purves (played the companion, Steven Taylor)

"I remember vividly the first episode of Doctor Who in November 1963. An Unearthly Child was a most remarkable piece of work, full of imagination that gripped the audience from the very first frame. I loved the whole concept.

"But the most exciting element was when I was offered the part of Morton Dill, an American hillbilly. When I walked into the rehearsal room in 1965 and met William Hartnell for the first time, it was a moment I shall always treasure. He was an actor I had admired in films like Brighton Rock and This Sporting Life, and for a young actor to be on the same set as him was just thrilling. Luckily for me, he liked me, and I became a regular on the show, just three weeks later, as Steven Taylor.

"I think the show grew in popularity because Bill Hartnell created an extraordinary leading character that really stood the test of time. The performance was quirky and totally original, like nothing that had been seen before. He was the foundation that meant that the show would be able to go through as many changes as it has done. And Sidney Newman's remarkable vision of a time traveller has regularly captured the imagination of recurring generations of viewers. Long may it continue, and with Peter Capaldi at the helm, I am sure that it will."

Terrance Dicks (writer who has created stories for many of the Doctors)

"I was pleased to hear of the discovery of a batch of lost Patrick Troughton shows in Nigeria recently. I was particularly happy about the recovery of The Web Of Fear. The show was in post-production when I joined Who in 1968 and I attended a showing on my very first day. They were desperately trying to make the roar of the Yeti sound less like a flushing toilet. They never did quite succeed.

"The Web Of Fear was the first Doctor Who story I had experience of professionally, though I had nothing to do with its inception. That said, it's a good Pat Troughton story, with Yeti in the London Underground and the first appearance of Nick Courtney as Colonel, later Brigadier Lethbridge-Stewart."

Michael Coen (writer of Doctor Who short stories)

"One of my favourite moments is during the David Tennant story School Reunion, which featured the return of the Doctor's companion, Sarah Jane Smith. When they initially meet, The Doctor recognises Sarah Jane Smith [played by the late Elisabeth Sladen] but not vice versa, as he has regenerated several times in their 25 years apart. Later, Sarah Jane stumbles across the Tardis and turns to see 'Mr Smith' who she now realises is The Doctor. 'I thought you'd died,' she says. 'I waited for you and you didn't come back.'

"There are complex, adult emotions examined here as the love of her life explains why he abandoned her. But it's that moment of recognition that stays in the memory."

Anneke Wills (played The Doctor's companion, Polly)

"I've just had the pleasure of recording Who's There?, William Hartnell's biography, written by his granddaughter and it was marvellous to find out all about him. What a complex and fascinating person he was. I was also reading all about his Scottish actress wife, Heather, and their early theatrical life. The wonderful Sussex cottage in the enchanted garden, hilarious inebriated adventures and how he loved the role of Doctor Who. It makes watching the recently released Tenth Planet, which was Bill Hartnell's last story, all the more poignant."

William Morrison (teacher, collector and fan)

"I was three years old when I first saw the show in October 1976. It was a television programme which my parents occasionally watched, in the background as they made tea. I ran to hide, to look away, but, unfortunately for me, the sofa was pressed flat against the wall and so I had no alternative but to look.

"I remember a hand. A blue, scaly, alien hand. No body. Just a hand. Crawling around the floor of what I will one day come to call a nuclear reactor, but which currently I have no words for. I'm only three, remember. A man in white reaches out for it and suddenly the hand grips hold of him, a fierce, possessive grasping, refusing to let go. And in that instant, I too am gripped."

Stephen Naysmith (Herald journalist and fan)

"I always see the maggots. When the Doctor Who theme kicks in, it is always the same. That tunnel of swirling shapes, the uncanny music, the sense of something rushing towards you triggers an old association that can't be broken.

"The Green Death must have been the first of the Time Lord's adventures I ever saw. But this 1973 Jon Pertwee tale of glowing deadly slime in a disused mine, which incubated giant wriggling housefly larvae, rooted itself in my young consciousness so deeply that it wasn't until they mucked about with the tune a decade later that the effect was broken.

"More recent versions of the theme still carry an excitement, but only the original music provokes that strange gut response, some kind of accidental hot-wiring between vision, sound and horrified race memory which encompasses all the fearful fascination which The Doctor's adventures still inspire in me. The original Ron Grainger theme, variants of which were used for the Doctor's first 20 years, still has the power to do it to this day."

Deborah Watling (played The Doctor's companion, Victoria)

"Doctor Who has almost always been on a Saturday at a time when all the family could watch it, but for children it had a special magic. I was just 19 years old when I joined the show and, in those days, the budget was not huge but it worked, and that was down to the whole crew.

"Patrick Troughton was my Doctor and he was such a wonderful actor - there was always a twinkle in his eye. He, Frazer Hines and I became like a triangle on the show.

"I watch the show now but it's very different. There was a charm to the old shows and, because it was black and white, it was especially eerie. The special effects might have been a bit plastic, but it was all in the imagination of the kids."

The Day Of The Doctor, a special 50th anniversary episode of Doctor Who, will be broadcast on BBC One on November 23 at 7.50pm and will be simultaneously screened in 3D at selected cinemas. Damien Love previews An Adventure In Space And Time, another of the anniversary programmes, in today's television section