Bonnie Langford stars as Melanie Bush in the BBC sci-fi series alongside Ncuti Gatwa, Millie Gibson (Ruby Sunday) and Lenny Rush (Morris), with the former EastEnders star giving her opinion on Gatwa.
The latest series from Russel T Davies saw an increase in budget after the BBC made a deal with Disney Plus, alongside a new release model which saw episodes coming out first on iPlayer at midnight.
Season 14 is coming to an end and will see the next episode - The Legend of Ruby Sunday - air on Saturday, June 15, and will delve into some of the mysteries that have been teased throughout the season.
Viewers will most crucially find out the matter of what's happening to Ruby and who her birth mother is - something many have been wondering for quite some time.
Langford first appeared in the BBC series between 1986 and 1987 and was the companion of the sixth and seventh Doctors - before making her comeback in the upcoming episode.
The former Dancing on Ice star recently discussed what it was like to work with Gatwa and told the BBC: "Working with Ncuti is fantastic. He has this great energy. He has such presence and charisma.
"He’s also a very generous actor. You really do feel you’re able to invest in the characters with him. It’s interesting because having worked with various Doctors over such a long period of time, you have to remember you're interacting with the same person but also not the same person.
"It’s quite a complex thing to think about. It’s not just a recast. It’s someone who is still intrinsically the Doctor but has a whole different new approach. It was great to work with Ncuti on that. He’s very instinctive and a real joy to work with."
Discussing what it was like to be called back into the magic of Davies' mind and writing, she added: "It was a huge surprise. It wasn’t something I expected.
"Although I had been involved with the Big Finish for quite some time, you never expect them to bring back an old character. I’m really thrilled. She’s been able to come back as a more fully formed character, which is great. She’s able to really contribute and use her skills."
There has been a lot of discussion surrounding the viewing figures of the latest instalment in the world of the Time Lord, but Davies recently clamped down on rumours it wasn't performing as well.
Speaking at a BAFTA Q&A event, he explained: "In coming back, I wanted to make it simpler and I wanted to make it younger. Those two things are often not discussed – you read reactions to it and people are missing that.
"It's simpler and younger – and it is working. The under-16s and the 16-34 audience as well is massive. It's not doing that well in the ratings, but it is doing phenomenally well with the younger audience that we wanted."
The synopsis for the upcoming episode reads: "Part one of the two-part finale. The Doctor and UNIT investigate Ruby's past. But as the Time Window reveals horrifying secrets from the fateful Christmas Eve when she was abandoned as a baby, the mysterious Triad Technology unleash the greatest evil of all."
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The exciting two-part finale comes as showrunner Davies recently admitted that he had already begun writing for the third season and told Radio Times: "I’m working on the fourth script now for season 3. It’s not actually commissioned, that’s still up in the air.
"But that’s the same for every TV programme. I shouldn’t say we’re confident, because that’s asking for a fall, but we’re very confident, to be honest. And we’ll just keep going.
"I can’t stop, that’s the problem! Ncuti’s off to do a play, The Importance of Being Earnest. And so were coming back after that. Amazingly, we might be shooting those scripts early next year. Those scripts have to be ready by about August, for prep. And it’s June.
"We’re not behind - but all my deadlines are just going to slap me in the face like mad. That’s my summer ruined."
