Director Euros Lyn comments that the production team had intended for Agyeman and Clarke to join "Torchwood" for its , but their careers led them elsewhere. When the characters interact with UNIT officers in "Children of Earth", Martha's absence is explained by her being on honeymoon. Head writer and executive producer Russell T Davies explains that Agyeman was cast in ' before "Children of Earth" had been officially commissioned. Because "Law & Order" offered her 13 episodes a year, she went with that over "Torchwood" which had been reduced to 5. In response, Davies created the character of Lois Habiba, played by Cush Jumbo, to be a "kind of a Martha figure", one with added innocence who is out of her depth. Agyeman does not rule out returning to the show at a later date, however. Davies reveals in his non-fiction book ' that Martha was also intended to appear in "The Sarah Jane Adventures" series two finale "Enemy of the Bane" in December 2008, but the character had to be replaced with classic series character Brigadier Lethbridge-Stewart (Nicholas Courtney) "at the last minute" due to Agyeman's role in "Law & Order: UK"; had Martha appeared, the character would have appeared in all three programmes in the franchise.