Chatting exclusively to Digital Spy at the Season Three press launch on Wednesday night, the acclaimed actor admitted he was open to the idea of linking up with past Doctors for a story, but that the passing of time may prove an insurmountable obstacle: "Sure... it's a lovely idea, [but] I just don't know about the practicalities of it, really. It's one of those shows and because it goes on for a long time it has this history."
"It gets tougher though... as the years move on," Tennant continued. "Let's be honest, we've lost three, unfortunately," he added, referring to the fact that William Hartnell, Patrick Troughton and Jon Pertwee - the first three actors to play the role - have all passed away.
Tennant reminisced about the impact such a reunion show had on him as a young fan, specifically the 1983 90-minute special: "I remember as a kid 'The Five Doctors' being the most important thing that had ever happened, so it's a nice idea. I just don't know if practically we could make it happen [again]."
The hit family drama has a history of gathering several incarnations of the rebellious Timelord together. The first such story was 'The Three Doctors' in 1973, featuring Hartnell, Troughton and Pertwee. Ten years later 'The Five Doctors' was screened, with Richard Hurndall taking over Hartnell's role with Tom Baker (via archive footage from the unbroadcast story 'Shada') and Peter Davison featuring alongside Pertwee and Troughton. The final story of its kind, to date, saw the Gallifreyan down to just 'The Two Doctors' in 1985, with Troughton joining Colin Baker to battle the Sontarans in Seville.
The third season of Doctor Who will begin on Saturday, March 31 at 7pm on BBC One with the episode 'Smith and Jones', featuring Freema Agyeman as the new companion alongside Tennant.