Showrunner Chris Chibnal is going all out for the BBC Centenary and Jodie Whittaker's last episode, bringing back classic 5th and 7th Doctor companions Tegan and Ace alongside the Master, Cybermen, and Daleks.

In a trailer titled "The Thirteenth Doctor's Final Adventure", we get a glimpse at Sophie Aldred's Ace and Janet Fielding's Tegan, returning much as Sarah Jane Smith and Jo Martin did with the 10th and 11th Doctors. Also like Sarah Jane Smith, Tegan's first Doctor isn't the one she's typically associated with. She appeared alongside Tom Baker's 4th but stuck around with the 5th for much longer.

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"In some ways, it was a very different experience to what it was like when I finished recording in 1983, but in many ways, it was very similar," Fielding said. "It was so lovely to be a working member of the Doctor Who family again."

"It's been quite a challenge to have such a big secret to keep, even from my family, and I couldn't be more thrilled and excited to have been asked back," Aldred added. "I hope everyone enjoys it as much as I adored being part of the TARDIS team again."

Ace was a 7th Doctor companion, staying right up until the show's cancellation before the Fox movie which lead the show to go stagnant for years until the 2005 revival. Her fate was left unknown, although she has since appeared in comics and novels. In the infamous Lungbarrow, Ace becomes Time's Vigilante, riding a Time Bike which is a vortex-hopping motorcycle. But she goes much further than that.

Interestingly, the 7th Doctor tried to mould Ace's mind so that she would become a Time Lord. This plan came to fruition as she attended the Academy on Gallifrey as per the audio book The Lights of Skaro - here, she became a Celestial Intervention Agency (CIA) agent, not to be confused with Earth's CIA. She was given a planet to observe, completed her training, and later went missing. The Doctor had to look for her as she ended up in a time lock on a 24-hour repeated day.

The audiobooks later detailed that Ace took part in the Time War, but she had her memory of Gallifrey and the War erased, being returned to Earth. We hear mention of her whereabouts in The Sarah Jane Adventures where it's said she's helping indigenous Australians. That's where she was last left off outside of a Coal Hill visit in 2016.

We'll see the next step in Ace's journey soon enough, and given Chibnal's tendency to pull from the nichest of Who lore, it isn't out of the question to expect references to these tidbits.

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