The “Doctor Who” Season 8 premiere airs Sunday and with filming more details have emerged on the show and the season finale. Chris Addison will appear in the season finale as a guest and some are pegging him to replace Jenna Coleman as Peter Capaldi’s new companion if the actress leaves. BBC has declined to comment on the rumors while showrunner Steven Moffat has refused to answer any questions.

Addison ("Skins") recently starred as Oliver Reeder in "The Thick of It" alongside Capaldi's Malcolm Tucker, making for a mini-reunion, Radio Times said. The "Doctor Who" Season 8 finale, the two-parter "Dark Water" and "Death in Heaven," is written by Moffat. Speaking to Radio Times, Addison said it was an easy decision to appear on the show, saying it's something he has now crossed off his bucket list.

'Doctor Who' Season 8 "Doctor Who" Season 8 premiere, "Deep Breath," sees the Doctor and Clara in Victorian London. Photo: BBC America

Following the rumors in the Mirror saying Coleman would leave after the "Doctor Who" Season 8 Christmas special, Ladbrokes set up betting odds for a possible replacement. Rose Leslie ("Game of Thrones" and "Downton Abbey") is the oddsmaker's favorite, at 14-to-1, with Addison at 16-to-1. These odds are relatively high, which could mean Ladbrokes is a bit skeptical about the Coleman rumors. Leslie's name is also new to "Doctor Who" and the actress has not been linked to the series or previously announced as a guest star.

Interestingly Samuel Anderson, who will appear as Danny Pink, is not among the candidates to replace Coleman in the betting odds. Pink will be a recurring character in "Doctor Who" Season 8 and is a teacher at the same school as Clara Oswald. Moffat said of the character,"Very soon now, Sam Anderson as Danny Pink will be entering the world of the Doctor. But how and why? Answers are coming later this year in Peter Capaldi's first series of Doctor Who!"

DoctorWhoTV revealed Moffat's episode guide teaser that appeared in Radio Times magazine, if you are inclined for some "Doctor Who" Season 8 spoilers.

The "Doctor Who" Season 8 premiere, "Deep Breath," airs Saturday at 8 p.m. EDT. The "Doctor Who" Season 8 premiere trailer can be viewed below.