The Monk was the first Time Lord other than the Doctor and Susan to appear in the series, although the term Time Lord would not be invented for another four years. The Monk also became the series' first recurring individual villain. It is evident that this story was produced in the 1960s: all the Monk's possessions are contemporary with that era, and he refers to the TARDIS as a "modern" police box. Only his gramophone is old-fashioned, and it was intended to be a tape recorder in the script.