"Hellooo," he says, his voice high and lilting, his accent as lovely as a single malt near a crackling fire. "How are ye?"
"I think the doctor is a very sexy dude, really, no matter who's playing him. It's just that the way the show is written nowadays invites girls and women in more than it did before. Russell gives it a kind of emotional heart that it hasn't always had, which means that the stories are still enjoyable to sci-fi or adventure fans, but now they connect with people who like more conventional drama as well."
"Well, it doesn't matter when you're wee, does it?" says Tennant. "You just go with it. If things are a bit clunky, your mind fills in the gaps. I was very frightened by the show myself as a kid, but it's the kind of fear that does you good when you're growing up. It scares the shit out of you to just the right degree, without pushing you over the edge. I think a few gentle nightmares is something we should all experience as children, so long as it's a safe fear."
"Well, it becomes a hobby, doesn't it?" Tennant says. "I think that's OK. I think Doctor Who fans are somewhat unfairly judged, like what they're doing is socially unacceptable. It's entirely harmless. At least they're not going out raping or murdering people. And it's a fantastic world to lose yourself in, which is probably why it has survived so long.
I'm not sure about New Zealand, but certainly in Britain, Doctor Who is a part of the cultural framework of our nation. It has an iconic status here, so the amount of attention and analysis is inevitably huge. Which can be daunting as an actor, actually. The show has a lot of devoted followers, and they're looking to you to not ruin something they love. It's quite a responsibility."
"I was about three when I decided acting was something I wanted to do, which is lucky, because I was far too young to realise how unlikely it was that I would succeed. If I'd been 12 I'd have probably thought, hey, hang on, people from Paisley don't really do that; I'll get a job in a shoe shop instead. But no, I had a really singular view of my path.
"I used to watch the telly and very quickly understood that there were people who spent their lives pretending to be other people so as to tell stories. I thought that was a fantastic thing to do. As soon as I left school I went straight to drama college and have made my living as an actor ever since."
Now that he's so widely lauded as a time-travelling, Dalek-trouncing alien hero, can Tennant ever go back to playing Romeo? "I certainly hope so. As an actor, you don't want to destroy your career by becoming so associated with one role that people will never accept you as anyone else. But the only other option was not to accept the part, and I couldn't do that, because Doctor Who is one of the best TV characters ever invented, I think.
"He's a free spirit and an anarchist, almost a force of nature, but he also has this immoveable moral centre to him. That's what makes him heroic, really. He's not heroic in the way that Superman or Batman is, or even Captain Kirk is. He's not a jock. He's not the strongest or the fastest, but he's the quickest witted, so it's about the triumph of the geek over the all-powerful, really, and I think that's very appealing. It was certainly very appealing to me as a child. It's wit over brawn. He's fast and anarchic and fun, but there's a degree of comfort attached for kids, because they always know where they stand with him. He's always got that strong moral compass."
He is also a staunch supporter of Britain's Labour Party, and once told a reporter he was amazed whenever he met anyone involved in the arts who voted Conservative: "I'd be thinking, `I have never met anyone from your world. What's it like? Do you roast children over open fires?"'
"Yes, well, I'm having the time of my life. I'm very content at the moment. The public appreciate me, I love my work, and here I am on my day off, sitting in sunny London in the middle of summer, overlooking the West End from my agent's very posh office. Life, as they say, is sweet."
A week ago, actor John Barrowman had a chair broken over his back, endured body punches and was dragged across a bar through broken "candy" glass, face down. For him, that's all in a day's work.
"I run an awful lot in this show in boots," says Barrowman, in the patio of a hotel here. "When I'm running they always shoot it full length because they love to see the coat trailing out behind me. And the coat is so heavy that sometimes your feet get caught up in the back of it and it trips you. 'Cut!'"
"My brother and sister and myself - my dad made us do manual labor because he said, 'If you want to do manual labor for the rest of your life you'll know that when you do it, it's a choice,' he said. 'But if you don't like it you'll understand the importance of educating yourself and being - if you decide what you want to do - being good at your craft or your skill.'"
Barrowman did the job for a full summer, hating every minute, until he used his considerable charm and logic to escape. "They started wanting me to do things. I looked at them and said, 'I don't know if you understand this, but my father is general manager of Caterpillar Tractor Co. and I know you'd not make a union man do this, so why are you making me do it as a student, which is completely illegal? They went, 'You're John Barrowman's son?' I said, 'Yes.' They said, 'Why don't we move you to the storeroom.'"
"I feel like a Brit AND an American," he says. "I think we became more Scottish when we left Scotland. Our patriotism to Scotland became strong but I was naturalized as an American citizen in 1985 and very proud of that. But my home is the United Kingdom. I live in London with my partner. We have a life there. We have two dogs and we have a home in London and one in Cardiff. We also have a home in the Midwest in Wisconsin and we're building one in Florida. One thing my dad always said was: 'Invest in property.' And I've done that."
"I don't think I'd ever leave the U.K.," says Barrowman, who costarred in the short-lived TV series, "Titans."
"I'd do what a lot of British actors do, come and work here, then go back. Because the unfortunate thing, if I were to come over here and live full time, Scott couldn't come with me. He wouldn't be recognized as my partner here by the government and the states and all that stuff. Whereas in the U.K. we're partners and looked on - I don't say gay marriage because I don't personally agree with it - but we have the same rights as married couples which we wouldn't have over here. So we have to take all that under consideration. It's unfair for me to ask him to pack up and leave because he couldn't work over here, either."
"Every time something happens to me is part of my dream coming true," he says.
"I'd love to do a major part in a film; that would be a dream and a goal. It's not something I actively go out and seek because if it's going to happen, it will. Most of the jobs I've done in America have come from the work I've done in the U.K. I've always believed if you do good work, it creates work. I let the agent and the manager do the pushing and let them do the seeking. If a movie part comes up I audition, if it's here in the U.S. I'll come here. I'm flexible."
BBC One has scooped two awards at the Edinburgh TV Festival, being named terrestrial channel of the year and taking best programme for Doctor Who.
Doctor Who producer Phil Collinson paid tribute to those delegates, saying that to receive the award "from young people coming into this industry is a particular honour".
He also praised the BBC, saying that without it, "Doctor Who would never be made, would never be so good and would never be so well supported".