'I always knew I wanted to tell a story where Dorian Gray encountered Sherlock Holmes,' says producer Scott Handcock, 'so I tentatively sounded out both Alex Vlahos and Nick Briggs, the actors who play the roles, way back before we even started work on the series. Both were so enthusiastic, I knew it had to be something special. Hence Christmas! Hence Tony Lee! And Ghosts of Christmas Past really is a lovely festive story.

'Pairing Nick with Alex has been especially fun because Sherlock's rational attitude has to come to grips with not only the supernatural machinations of the story, but also with Dorian himself. They're the same age too, at least on paper - but in terms of behaviour and thought processes, they're wildly different people. It's a really interesting dynamic to play with!'

The story, set during the Christmas of 1912, finds Dorian and Sherlock both return to London unexpectedly, where they are confronted with a series of mysterious happenings. Joining Alexander Vlahos and Nicholas Briggs for this adventure are Rupert Young (Merlin's Sir Leon) as James Moriarty, Rebecca Newman as Sibyl Vane, with other parts played by Richard Nichols, Seán Carlsen, Wilf Scolding, Lorna Rose Harris, Antonio Rastelli, Alexander Griffin-Griffiths and Sophie Melville.

The Confessions of Dorian Gray: Ghosts of Christmas Past will be available via download in December. The five-part series of half-hour instalments - on download only - is also available to pre-order now and will be released from the end of October.