in 1991, lwt commissioned 10 episodes for series 4. it became the most popular series of the drama. paul knight had appointed brian clark as the fire brigade advisor. the writers, directors, and clark decided on a climax to the fourth series. the mental state of one of the main characters deteriorates after being buried alive under a collapsed wall. this is during a spectacular 20-pump warehouse fire. series 4's climax won the programme a record rating of 18.86 million viewers.