Derek Jacobi said: "The Master’s a great part to play – he's very dramatic, but he's also very funny. Occasionally he gets a bit big-headed, but he has many layers to him. And he's a wicked old fart, isn't he? The hero who’s a knight in shining armour is really a boring old sod. He’s got to have faults, and the Master's full of faults."

Producer Robert Valentine added: "When the Master returns, we’re going to see him facing an existential crisis. The Daleks and the Time Lords both want him dead, and he wants out of the Time War. However, he knows in his hearts of hearts that there is no way out, and a desperate, despairing Master is a very deadly Master indeed.

"There are some deliciously dark and wickedly funny adventures in store, and at the centre of it all is Derek Jacobi’s towering performance. It’s been an absolute dream working with Derek, and through these stories we’re getting to see many different sides of his Master’s character.

"Watching him transform from a charming lady-killer one minute to a rat in a trap the next, or from a kindly grandfather into the very devil has been a thrill. This is very much a Master who sees no hope for the universe or for himself, and is trying to console himself by helping it burn. And he'd very much like you to join him."

Writer Lizzie Hopley said: "I like dark stories and the ones I've written for Sir Derek Jacobi's Master are my favourite. To write for such a skilled actor allows you to include layers within lines and scenes which another may miss. The twists and turns in the plot were more challenging than other audios I've written and so satisfying to work out."

The final episode's writer, Adam Christopher, who is best-known as a New York Times bestselling novelist, said: "Writing Doctor Who was always the dream, but I could never have imagined that my first full-cast Big Finish would star one of the greatest British thespians, Sir Derek Jacobi! From start to finish, The Blue Shift Ritual was a total joy, not only to write but to see and hear come to life thanks to Sir Derek's deliciously devilish performance and the incredible ensemble cast.

"In The Blue Shift Ritual – which takes its title from a line in Paul Cornell's Timewyrm: Revelation – we get a glimpse of a real Doctor Who rarity: the time travel experiments of Ancient Gallifrey. And if the Master was going to stage his own death, what better way is there than to destroy the entire universe itself?"

Sir Derek Jacobi © Tony Whitmore