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The end is nigh. Doctor Who returns at Easter for the first of four 2009 specials that will culminate in the 10th Doctor, David Tennant, regenerating into the 11th, Matt Smith. When Tennant leaves, so does Russell T Davies; Steven Moffat will replace him as head writer and executive producer.

The partnership of lifelong Whovians Tennant and Davies has seen the show cement itself in the national psyche, exterminate all competition in the ratings and scoop award after award. During a break from making the next special in Cardiff, Tennant and Davies steeled themselves with a tray of BBC sandwiches to consider past, present and future. Very Who.

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Russell T Davies People are going to be Doctor Who-deprived this year, so it’s got everything in it: CGI monsters, prosthetic monsters, army, police, an alien planet . . . It’s our last chance to have a bit of a laugh. Now the Doctor’s facing the end of his life, it’s going to get dark.

David Tennant Some of it was filmed in Dubai, and there were sandstorms . . . We were despairing. I’d look into the distance and go (Acting), “What is this strange alien world?” Well, I couldn’t actually open my eyes to look at it. The Exfoliation of Doom would be a good subtitle. My hair was full of sand. And blonde. I looked like Tina Turner.

Come the final curtain, will there be a dry eye in the house?

RTD I should f***ing think not!

DT Well, I cried (when I read it).

Did you make a pact to leave together?

DT We talked about it. It wasn’t a pact . . . I’d sort of decided. But then I nearly changed my mind again.

RTD We had dinner and chatted about it a few years ago. It just felt right. The BBC asked me to do a series five, but I didn’t shift at all.

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