David Llewellyn is a Welsh novelist and script writer. He grew up in Pontypool and graduated from Dartington College of Arts in 2000. His first novel, Eleven, was published by Seren Press in 2006. His second, Trace Memory, a spin-off from the BBC drama series Torchwood, was published in March 2008. Everything Is Sinister was published by Seren in May 2008. He has written two novels for the Doctor Who New Series Adventures: The Taking of Chelsea 426, featuring the Tenth Doctor, and Night of the Humans, featuring the Eleventh Doctor and Amy Pond. In addition to writing novels, Llewellyn wrote the Bernice Summerfield audio play Paradise Frost and the Dark Shadows audio drama The Last Stop for Big Finish Productions. Llewellyn lives in Cardiff.

Simon Guerrier is a British science fiction author and dramatist, closely associated with the fictional universe of Doctor Who and its spinoffs. Although he has written three Doctor Who novels, for the BBC Books range, his work has mostly been for Big Finish Productions' audio drama and book ranges. Guerrier's earliest published fiction appeared in Zodiac, the first of Big Finish's Short Trips range of Doctor Who short story anthologies. To date, his work has appeared in the majority of the Short Trips collections. He has also edited three volumes in the series, The History of Christmas, Time Signature and How The Doctor Changed My Life. The second of these takes as its starting-point Guerrier's short story An Overture Too Early in The Muses. The third anthology featured stories entirely by previously unpublished writers. After contributing two stories to the anthology Life During Wartime in Big Finish's Bernice Summerfield range of books and audio dramas, Guerrier was invited to edit the subsequent year's short story collection, A Life Worth Living, and the novella collection Parallel Lives. After contributing two audio dramas to the series, Guerrier became the producer of the Bernice Summerfield range of plays and books, a post he held between January 2006 and June 2007. His other Doctor Who work includes the audio dramas, The Settling and The Judgement of Isskar, in Big Finish's Doctor Who audio range, three Companion Chronicles and a contribution to the UNIT spinoff series. He has also written a play in Big Finish's Sapphire and Steel range. Guerrier's work is characterised by character-driven humour and by an interest in unifying the continuity of the various Big Finish ranges through multiple references and reappearances of characters. As editor he has been a strong promoter of the work of various script writers from the Seventh Doctor era of the Doctor Who television series