Passionate Productions for BBC ; produced for NOVA by Holt Productions, LLC ; WGBH Boston ; produced and directed by Jemima Harrison and Sarah Holt ; writer for the BBC, Jemima Harrison ; executive producer for the BBC, Richard Klein ; senior executive producer, Paula S. Apsell
a Nova production by Ark Media in association with Realization Pictures ; written and directed by Phil Bertelsen ; produced by Phil Bertelsen and Jane Teeling