Russell T Davies wishes he'd made Dame Judi Dench the first female Time Lord on 'Doctor Who'.

Dame Judi Dench

Dame Judi Dench

The sci-fi show's former showrunner regrets not taking the chance to have a big name appear as the iconic character in 2008's 'The Stolen Earth', when star David Tennant's incarnation was shot by a Dalek and started to regenerate before using a severed hand to heal his wounds but retain his body.

During a watchalong this week, Russell tweeted: "If I had my time again... I'd have MILKED that. I'd have cast a whole new Doctor, a superstar for ONE scene.

"Ian McKellen! Judi Dench! Have them run around the Tardis. Then discover the hand, and regenerate back. IMAGINE!! Why didn't I?! (sic)"

If the 59-year-old writer had introduced Judi - even as a brief cameo - she would have become the first female Doctor nine years before Jodie Whittaker made history with the role.

The 'Stolen Earth' episode was special for Whovians as several companions - including Captain Jack (John Barrowman), Rose Tyler (Billie Piper) and Sarah Jane Smith (Elisabeth Sladen) - all appeared, and Russell even thought about bringing back a character from the show's classic era.

He explained: "This story was planned a long way in advance, and as proof of that... All sorts of characters could have been in Harriet's place, running the Subway Network!

"I spent a long time thinking it could be Elton Pope from Love & Monsters, or I even toyed with an old Doctor Who companion appearing out of the blue.

"Polly running it from India! Or Tegan! Imagine. (sic)"

Instead, Harriet Jones (Penelope Wilton) led the network, which marked her first appearance since the first series of the show's revival in which she appeared opposite Christopher Eccleston's Ninth Doctor.