As Doctor Who fans know, companions come and go over time, but every time someone leaves it is always a sad occasion. Ahead of Doctor Who's 2021 holiday special, "Revolution of the Daleks," star Jodie Whittaker confirmed that this would be the last story for widower Graham O’Brien (Bradley Walsh) and his step-grandson, Ryan Sinclair (Tosin Cole). While the reasons for their departure might seem bolted-on to some, their reasoning follows a long tradition amongst former companions.

There is always a “real world" reason that characters are written out of the show, and those reasons are unambiguous - both Walsh and Cole are involved in other TV productions. Walsh is a constant presence on UK television, having done game shows, talk shows, and more. At present, he has been cast in a new production based on The Darling Buds of May. He is also the host of two ongoing game shows, The Chase and Cash Trapped. There’s also an occasional travel series with his son, Barney, subtitled Breaking Dad. He is, in short, in demand.

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Cole, who appeared as Lieutenant Bastian in 2015’s Star Wars: The Force Awakens, will spend 2021 starring in a new TV series called 61st Street, set in Chicago. He'll also be appearing in movies including Pirates, The Souvenir: Part II, and Ear For Eye. With filming for Doctor Who season 13 already well underway, there was no way for Walsh and Cole to stay with the show and continue their non-Who careers. Both have spoken highly of their time with Doctor Who and the camaraderie they had with Whittaker and Mandip Gill (Yaz). However, even with the long gaps between seasons, Doctor Who is a very demanding show to film. Speaking to Hello Magazine, Walsh described the demanding production pace: "This is ten months of ramming speed. That's what it is. I'm in my 60th year. It's tough. It's hard. It's relentless. It really is. This ain't an easy gig."

How Doctor Who's Holiday Special Said Goodbye To Ryan and Graham

The Thirteenth Doctor is surrounded by Daleks in her prison outfit, as Captain Jack, Ryan, Yaz and Graham prepare for action.

In "Revolution of the Daleks," we meet up with the familar "fam" after the Doctor has disappeared (arrested and imprisoned by the Judoon at the end of the previous episode, "The Timeless Children." Unbeknownst to the Doctor, in the lives of her companions she has been missing for 10 months (the real gap between the two episodes, amusingly) with no explanation.

For Ryan, this has been a period of reassessment and introspection on his life. The character had always been somewhat conflicted about the time he was missing in the lives of his friends (as seen in other episodes), and in "Revolution of the Daleks" he lets the Doctor know, in the quiet moments, that he feels he has worked out his purpose in life, and it is to watch over his “home” - planet Earth.

Graham at first makes it clear he plans to continue adventuring with the Doctor, but given a choice between his own desire to see more of the universe and an increased role in Ryan’s life as his grandfather, he ultimately chooses the latter. At the end of the special, Graham and Ryan are seen planning their own new adventures on Earth, investigating unusual reports of possible aliens.

This follows in the footsteps of previous companions of the Doctor, most notably Sarah Jane Smith (as seen in her spin-off series), who became an investigator of paranormal events. Likewise, Jo Grant (another companion of the Third Doctor) devoted her post-TARDIS life to saving the Earth through environmental causes. Ace, a companion of the Seventh Doctor, began a global organization called A Charitable Earth, while Martha Jones and Mickey Smith appear to have become married alien hunters (as seen briefly in "The End of Time, Part II"), to say nothing of the heroics of Captain Jack Harkness.

While Yaz’s story with the Doctor continues, Ryan and Graham appear to have understood that their fates lie elsewhere. For series 13, a new companion named Dan (played by John Bishop) will join Yaz and the Doctor.

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