Warner Bros. Television ; TNT ; The Shephard/Robin Company ; Walking Entropy ; executive producers, James Duff, Greer Shephard, Michael M. Robin, Adam Belanoff, Mike Berchem, Duppy Demetrius ; created by James Duff
created by Mark Gatiss, Steven Moffat ; produced by Sue Vertue ; executive producer Masterpiece, Rebecca Eaton ; executive producer for BBC, Bethan Jones ; executive producers, Mark Gatiss, Steven Moffat, Beryl Vertue ; Hartswood Films production for BBC, Cymru Wales in co-production with Masterpiece