Peter Davison was in charge of the Tardis for Doctor Who's 20th anniversary in 1983.
A special story, The Five Doctors, featured Davison's fifth Doctor alongside Richard Hurndall (as the late William Hartnell's first Doctor), Patrick Troughton's second Doctor and Jon Pertwee's third incarnation.
Fourth Doctor Tom Baker, who declined to take part, appeared via unused footage from his era.
At the age of 29, Davison was the youngest actor to play the role (until 26-year-old Matt Smith was cast at the 11th Doctor).
Davison's daughter, Georgia Moffett, is married to 10th Doctor, David Tennant.
In this interview, Peter Davison recalls his reign as a Time Lord, names his best and worst stories, and reveals his plans for the 50th anniversary.
What can you say about your involvement in the 50th anniversary celebrations?
Virtually nothing. All I can say is that the 50th anniversary is not just about the 50th anniversary special - there are a lot of things around that particular programme that people have been working very hard on - "the other content" as the BBC like to call it. I'm hopeful that the fans will enjoy what's on offer to them.
I was the first Doctor who'd grown up watching the series, so to have Patrick Troughton - who was my favourite Doctor - and Jon Pertwee in the programme with me - and Richard Hurndall playing William Hartnell's character - was a huge thrill.
I was the incumbent, so theoretically I was the main man. So I enjoyed it immensely.
I was a little disappointed because producer John Nathan-Turner had said: "I haven't got too much stuff with all of you together, because I'm afraid there will be too many egos flying around the set." But that would not have been the case.
The great thing about Doctor Who is that everyone has their place. I'm forever the fifth Doctor, Tom the fourth, and so on. We can happily co-exist, and we all have various things going for us. I could move quicker than most of the classic Doctors.
As a Troughton fan, what's your reaction to the recent news about the lost episodes being found in Nigeria?
It's fantastic news, and it opens up the hope there may be others lying around in relay stations somewhere. It's always been the great tragedy of those early stories that the BBC wiped the tapes.
Do you remember watching the first William Hartnell story in November 1963?
I was 12. It was a weird time because it was the day after Kennedy had been shot and I didn't really understand much about what that meant except that everyone around me was in a state of shock.
They repeated it the following week so I actually watched it twice, and I remember being drawn in. It was so mysterious. There was a granddaughter living with her grandfather in this yard in a police box. I just wanted to see more of it.
Like Peter Capaldi, you were already a household name when you were cast as the Doctor. How do you think he will find it?
Now it's so accepted that you have different Doctors. Obviously he'll get the reverse flak that I got, to an extent, in that he's much older than the younger viewers are used to, and I was the youngest.
Which stories are your classics, and which would you rather were lost in Nigeria?
When I grew up watching Doctor Who, I loved the ones where he tinkered with history, so I liked The Visitation, where I started the Great Fire of London. I loved Earthshock because Cybermen were my favourite monsters.
My favourite story of all was my last one, The Caves of Androzani, because we had a classic Doctor Who writer, Bob Holmes, and it was directed by Graeme Harper who directed far more filmically than it had ever been done before.
We did a story called Timeflight - which was very good story, but we had run out of money. We filmed the prehistoric landscape of Heathrow airport in Studio 8 [at TV Centre] with a model Concorde in the back of the studio. The monsters were bits of foam.
We didn't do the story justice - I wouldn't mind seeing that in a relay station in Nigeria!
I had to make the decision absurdly early. It was at the end of my second season. The producer asked about staying beyond a third year and I said I would call it a day because that had been my plan, as suggested by Patrick Troughton. Do three and get out, he said.
I stuck with that. I had a chance to change my mind, but I thought that would be chickening out, and there were other things I wanted to do.
It's never easy because you're playing this iconic character. I've had this conversation with David Tennant - you make the decision to leave and you're happy with it, but when you actually get to the day in the studio when the next Doctor comes in and replaces you it is the most gutting moment.
I'm sure it will, but the great thing about Doctor Who is that it's got into the position of almost regenerating itself. The fans that grew up watching the programme are now running the programme, they are writing the programme, they are in it.
As long as the programme maintains those high standards and inspires actors and writers and directors to want to be in it, I don't see any reason why it can't carry on.
And you have created your very own Doctor Who dynasty, with David Tennant as your son-in-law.
Yes, my children and his children are trying to line themselves up for future Doctors. It's going to be very difficult for anyone else to get a look in.
I'll be at a convention with lots of fans. I think it's going to be a busy day!