Hinchcliffe was reluctant to use characters and monsters from the series' past: the Daleks, the Cybermen and the Sontarans only appeared once during his tenure, and these stories were commissioned by Barry Letts. The Master and the Time Lords returned for one adventure, "The Deadly Assassin", at the suggestion of script editor Robert Holmes, but were portrayed very differently from their previous appearances. The character of Brigadier Lethbridge-Stewart and the United Nations Intelligence Taskforce made their final regular appearances in Hinchcliffe's second season.