This is not a drill: David Tennant and Billie Piper have reunited for a particularly candid and intimate episode of the former's hit podcast.

In a wide-ranging conversation, Piper opens up about the pressure she felt while making the first post-relaunch season of Doctor Who in 2005. "It was new ground and using technology that Hollywood used," she recalls. "It was a huge gamble. And we were all quite aware of that when we were shooting it, which sort of meant that we couldn't enjoy it as much as we did in our second [season]. Everyone went mental for it, and that was a really nice feeling going back in."

Tennant, who joined Piper a year later for season two, recalls that working on the cult BBC America series "wasn't like filming a normal job."

"When we were on location, we'd be surrounded by crowds," he says. "There was people buzzing round wherever we went. We were bundled in and out of cars and whisked into places through the back door and chased by photographers. It's the closest I've ever felt to imagining what it must be like to be a pop star."

Before she was cast in Doctor Who, Piper was already known in the U.K. as a pop star herself, who had scored three number-one hits with the singles "Because We Want to," "Girlfriend," and "Day & Night." She later stepped back from the public eye for three years before launching her acting career.

Asked by Tennant whether pop stardom and appearing in a show as high-profile Doctor Who were "relatable experiences," Piper replies: "They were. Sometimes I found that quite hard because, I had three years just living a life that wasn't particularly normal, but it wasn't 17 hours a day selling records and being very actively public. I really enjoyed those sort of sloppy years, and then going back and starting Doctor Who reminded me about that. The sort of pressure and responsibility was a big part of it because I was in my early twenties and quite wild. And then you're the face of a family show. I found that really hard."

You can listen to an excerpt from the episode here.

You can listen to the full episode of David Tennant Does a Podcast with.. Billie Piper now via all the usual podcast providers.

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