From series 1-3 The Bill was aired in a post-watershed timeslot. Throughout this period there were several episode featured strong scences of nudity.
The first 3 seasons were shown in a post watershed timeslot which allowed for strong scenes of nudity in some episodes. In season 4 when the show moved to a pre-watershed timeslot, nudity is always mild if featured in an episode. Sex is often referred to but no strong sexual activity is ever shown.
Some Episodes feature storylines of rape/sexual assault.
Season 1 Episode 5 "It's Not Such a Bad Job After All" contains a scene with full frontal female nudity. This is the only full frontal nudity in the entire series (out of 2425 episodes)