The festive instalment titled ‘Twice Upon a Time’ will see the Scottish actor make his last appearance as the 12th Time Lord after three years on the BBC One Show.
And his co-star David Bradley, who plays the role of the first Doctor William Hartnell in the episode, admitted Peter, 59, was close to tears when they were shooting scenes.
In an interview with TV & Satellite Week, he said: “At one point Peter and I looked at each other and I wondered who was going to well up first!
“Peter has been a wonderful Doctor and it was an honour to be a part of his final appearance. This was also the final story for head writer Steven Moffat, so it was very emotional.”
The 75-year-old also revealed some details about the upcoming episode as he teased there will be a clash between his character and the Time Lord.
David explained: “The Twelfth Doctor is rather shocked by this old guy with his 1960s sensibilities and his non-PC attitude to things.
“For me, the comic energy between them is a lot to do with the two different worlds they’re coming from, but gradually there’s mutual respect and, by the end, acknowledgment.”
The Christmas special will see Jodie Whittaker take over the role of the Doctor in the final moments as Peter regenerates.
And David is full of praise for the Broadchurch star as he said he couldn’t wait to see her in action.
He added: “Jodie is capable of great emotion and she’s got a wicked sense of humour. I can’t wait to get a glimpse of her in the Tardis!
The full interview with David Bradley can be found in the latest issues of TV & Satellite Week out now.