David Tennant has revealed he was originally meant to return to 'Doctor Who' for a flashback episode.
He is back for three special episodes as part of the BBC show's 60th anniversary celebrations, and while he'll be playing the new Fourteenth Doctor rather than reprising his role as the Tenth, that wasn't always the case.
Initially, his comeback alongside Catherine Tate (Donna Noble) would have been set during season four, but the duo will instead return in new episodes 'The Star Beast', 'Wild Blue Yonder' and 'The Giggle'.
He told the new issue of Radio Times magazine: "It would have been an unseen adventure from years before.
"[Showrunner Russell T. Davies] immediately had an idea for a story, which I’m not going to mention because I don’t think it’s yet seen the light of day.
"It certainly wouldn’t have been part of an ongoing story. But I hope one day he does use it, because it sounded great."
Speaking about returning to the show and potentially ruining his legacy after quitting the show in 2010, he said:
"I hadn't thought about it like that.
Thank God I made it to this point! It never really occurred to me to worry about that. Perhaps it should have done… but with Catherine [Tate] being part of it, and with Russell [T Davies] writing the scripts, I never actually worried about anything other than my own ability to run as fast as I used to."
He continued: "'The first conversation we had about it was very casual.
"Russell and Catherine were talking about the notion of: "What if we got the band back together for one last special? But David would never do it." And I said, "What do you mean I'd never do it? I'd do it in a shot." And then suddenly, we were back for three in a row.
'I mean, why not? It was such a joyous time, and these are people I love as humans, and certainly love as people to work with. And Doctor Who is something that will always be hugely important to me."
While the three episodes will mark the end of Tennant's latest run in the TARDIS he has admitted there is always a chance he could return in the future.
Speaking to SFX magazine, he recently said: "I think it would be disingenuous to imagine that I might never be asked again, because history would indicate that it was always a possibility.
"So I’m not going to say never because I don’t think anyone would believe me.
"That doesn’t mean I know that I ever will. But I suppose until I can’t run down a corridor it’s always a possibility. But I promise to have no plans."