Doctor Who's Russell T Davies explains how Varada Sethu's cameo in 'Boom' led to her being cast as Ncuti Gatwa's companion

Ncuti Gatwa's Doctor will be joined by a new companion for his second season in the TARDIS, but she's not an entirely unfamiliar face. Varada Sethu, who'll join the Doctor and Millie Gibson's Ruby Sunday for Doctor Who season 2, also had a small role in a season 1 episode – but she'll be playing a different character next time. 

"I think we might as well just be simple with this, because we've already said she's not coming back as Mundy Flynn," Davies tells SFX magazine in the new issue, which hits newsstands on July 10 and features Doctor Who on the cover. "It's one of those very simple situations, like with Freema [Agyeman, who appeared in 'Army of Ghosts' before being cast as companion Martha Jones]: when you cast a great actor, you need a new companion."

Sethu played Mundy Flynn in 'Boom', the third episode of season 1. Written by former showrunner Steven Moffat, it takes place on the wartorn planet of Kastarion 3, and Mundy is a marine who the Doctor and Ruby encounter after the Doctor steps on a landmine. 

"I was watching, like, the fifteenth edit of 'Boom', loving her," Davies continues. "Every time I watch her, I think, 'God, she’s brilliant', I literally think she's brilliant. I used to watch her thinking, 'God, what a shame we can’t work with her again.' I was thinking, 'Should we go back to the 51st century, could we meet her again?' and then I suddenly went, 'Oh, let’s just cast her again. We've done that before. Lovely.' 

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"The relief that went around the entire production and the BBC, everyone went, 'Oh, great.' It was the most instant yes you’ve ever seen. So she didn't even have to audition," he continues. "We then invited her to come in for a meeting, but she thought she was coming in to audition [laughs] and it was the other way round. It's like we were auditioning. We were wanting her to like us so much that she'd want to come back! We had a great meeting. She was kind of amazed and delighted. Lovely." 

Davies concluded by teasing what's to come, claiming: "Good stuff ahead. Completely new character, again, a completely new story and that's a great new story that will run across eight episodes."

Doctor Who season 1 is streaming now on BBC iPlayer in the UK and Disney Plus worldwide. Read more in the latest issue of SFX magazine, which features Doctor Who on the cover and is available from Wednesday, July 10. Check out what to look for on newsstands below... 

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