Producer David Richardson said: "The main story of Once and Future is over, but this is an afterward, a final chapter, which unites two incarnations who have been lost to the Doctor’s consciousness. It’s the Fugitive vs War Doctor, with some old friends and foes joining the fray. And, significantly, this is Jo Martin’s first performance for Big Finish – welcome aboard, Jo, you are absolutely brilliant."

Jo Martin said: "Doing Doctor Who on telly was life-changing. It’s led to more opportunities than I’ve ever had before. And now I'm here, doing the audio, which is just incredible. And meeting these guys who have been here so many years, and are still looking fabulous and sounding great – it’s all good!"

Her co-star Jonathon Carley added: "I recorded the surprise twist appearance of the War Doctor at the end of The Union but assumed that was it. But then when I found out about Coda and who would be in it, I was just giddy.

"To pair these two ‘secret’ Doctors together, it takes that antagonism of different incarnations to a whole new level. Not so much two Doctors teaming up together, at least not initially, but actually fighting each other. Jo’s Doctor is really no-nonsense and quite formidable – it was a journey of discovery to react to that, because we’ve seen so little of her Doctor on screen, it’s really new and exciting."

Jo Martin © Tony Whitmore

Imogen Stubbs © Tony Whitmore

Jonathon Carley © Tony Whitmore

Jonathon Carley, Jo Martin, Lisa Bowerman © Tony Whitmore