Just after the press screening of the upcoming Doctor Who special, The Waters Of Mars, which is being broadcast on Sunday 15th November at 7pm (like, er, you didn't know that), Russell T Davies and David Tennant took to the floor to answer questions from the assembled throng. That said, given the impact of the screening of the episode just minutes before, it took a while for the questions to come.

"That was a barrel of laughs," joked Davies of the episode as we tried to take it all in (he ain't kidding, either - there are one or two drops of humour in the first third of the episode, but then it's as serious as Doctor Who gets). But then things did start to get going, and here are the highlights, with spoilers cut out...

How would you class that episode? Is that the darkest and scariest you've done? Is that one of the scariest?

DT: Most probably, yeah, I think. It tells a different sort of story I think. [had to chop quite a lot there I'm afraid, as David Tennant talked about the unusual path of the Doctor in this particular episode]

RTD: It wasn't really scary. It was tense.

Russell, are you still thinking of Doctor Who stories now you're finished on the show?

RTD: I don't really, no. Because I knew I was finishing two years ago so I stopped then. [pauses] There's a good Twitter Doctor Who story. In 140 characters! [laughs] No, to be honest.

On whether the episode is still aimed at children, given the darkness of it...

RTD: Absolutely. Have you ever read a Harry Potter book? What I love about that [episode] it's a complicated story. It's very intelligent. The Doctor's moral choices there are caught up in a temporal conundrum, and six-year-olds could follow that. Absolutely easy...and I think that's fantastic television for children.

On the forthcoming end of the current generation of the Doctor, and where the story is heading...

DT: Well I think this gives you a hint. [Tennant then discussed spoiler-y things from the end of the episode, which you probably know, but we don't want to spoil just in case]

RTD: Davros told him at the end of the fourth series that he was responsible for many people's deaths, and that all these things are coming to an end.

This [episode] also shows why he travels with a human companion. He would have had someone to talk to, and found a different way out of it..

Do you feel that you've wrapped it up satisfyingly?

DT: Yeah, I think it feels like we tell a big end of an era story and at the same time handing it on. Which I think is important in this show, which let's face was going a long time before we showed up, and no doubt will continue into the far distant future. I think we tell a big old farewell story and then hand it over in rude health.

[At this point, our recording struggled to pick up the exact words. But this is where Russell T Davies talked about the first scene of the Christmas specials being shown on Children In Need, and there was also chat about whether souvenirs were taken from the set.]

With pictures leaking out of the new Doctor Who series, do either of you feel any regret at all?

RTD: I'm straight on there! (mimics tapping at computer)

DT: It's weird. I remember before it was the case that that will probably happen, and that we'll probably start seeing snaps of them on street corners and wearing anoraks. I was nervous about how I'd feel about that. I'm thrilled that it's carrying on, and everyone that's there is a great choice. But I've been really excited to see that it's going on, teased by what I'm seeing. I just can't wait to see it. I suppose it's because I remember what it felt like as well, to be where Matt is now. I'm really excited to see someone else starting out on that journey.

To Russell T Davies: are you writing or working on an American version of Doctor Who?

RTD: No, absolutely not. Absolutely not. No. As you know, I lie my way through these things, but no, absolutely not. I bet you £100 that I'm not. [RTD also bet members of his family on this fact. He seems very adamant!]

Do you feel that everything you wanted to do with the series you've done? And to David Tennant, is there anything you ever wanted to do as the Doctor that you haven't?

RTD: I do feel that. I think when I started I didn't imagine it would go so far with it. So I feel more than happy and vindicated.

DT: I got to do so many more things than I ever imagined I would, let alone working alongside some incredible actors. All the things I got to do! Hanging off things, being blown up, wearing make up on myself of a 9 million year old man. All these things that I'd never have dreamed of. So I didn't have a checklist of things where I said when am I going to get to ride a unicycle?! It was just an incredible, continually surprising trip. I wouldn't have had it any other way.

We know some of the companions are returning for your final episodes. Can you confirm which ones?

DT: Well you saw Catherine Tate, Bernard Cribbins, John Simm as The Master, although he's not a companion!

RTD: Jackie King, who plays Donna's mom Sylvia is coming back. And The Master's wife. And The Ood!

[At this point, both Russell and David paid tribute to Barry Letts, to whom the episode is dedicated. Sadly, too much paper rustling near our microphone meant we couldn't get the exact words down. David Tennant did note that Letts was the only person to write, produce and direct Doctor Who, though]

The Q&A then wound down with a couple more questions about favourite episodes (they wouldn't pick one!) and the correspondence they get from children regarding the show. And then the pair dematerialised from the room, with us hopefully all set to meet again for the Christmas specials...!

Our review of The Waters Of Mars will be live on Sunday night. It's got so many spoilers in it we don't want to put it live until the credits start to roll!