Nicholas Briggs said: "My wife had been editing one of Richard’s books and said to me, he writes beautifully. He also knows his old Doctor Who and has a very clear sense of the Third Doctor era, so I asked him for ideas for Third Doctor stories. He sent this one pitch and it had something about it that I really liked. It felt like Doctor Who, but also like an old-fashioned Sunday afternoon teatime adventure.”

Richard James added: “Nick’s written not just some of the best Doctor Who for Big Finish, but some of the best scripts I've ever heard. I love his Eighth Doctor and Lucie Miller stories; I remember listening to those avidly. So I was delighted to co-write with him.

"And I never knew I was such a big fan of the Third Doctor era until I started writing the script and suddenly I could hear the Doctor, the Brigadier and Liz Shaw in my head. It was quite extraordinary. Liz is really interesting, and was criminally underused at the time, so I gave her the opportunity to come to the fore and do her own investigating.

"It was amazing hearing those words coming back to me by the people who were born to say them. Not just the likes of Tim Treloar, Daisy Ashford and Jon Culshaw as the triumvirate that we all know and love, but also the incredible supporting cast."

Tim Treloar © Tony Whitmore

Jon Culshaw, Richard James, Nicholas Briggs, Glen McCready, Tim Treloar, Callum Pardoe, Daisy Ashford, Roslyn Landor, Susan Harrison, Mark Elstob