Speaking to BBC America, he said “I thought about the Doctor traveling on his own and it always faintly depresses me, I’m not sure what he does on his own but I don’t think it would be healthy. He’s far too old and he’s seen too much.”
The executive producer goes on to explain his thoughts on the importance of the companion: “The story of Doctor Who is always the story of the companion, It’s always their story.
“It was Rose Tyler’s story, it’s Amy Pond’s story. The story of the time they knew the Doctor and how that began; how it developed and how it ended.
“The story begins again, not so much with the new Doctor, but with the new companion. It is their story. The Doctor’s the hero, but they’re the main character.”