a Hartswood Films production for BBC Wales in co-production with Masterpiece ; co-created by Mark Gatiss & Steven Moffat ; written by Mark Gatiss, Steven Moffat and Steve Thompson ; series producer Sue Vertue ; executive producers Beryl Vertue, Steven Moffat, Mark Gatiss, Bethan Jones ; directed by Jeremy Lovering, Colm McCarthy, Nick Hurran
Harmony Gold and Banque et Caisse D'Epargne de L'Etat, Banque Pariabas Luxembourg in association with Silvio Berlusconi Communications present ; produced by Frank Agrama, Alessandro Tasca, Danielle Lorenzano ; written for television by Bob Shayne and H.R.F. Keating ; directed by Peter Sasdy