Complex sentence: Prior to appearing as Myra she had appeared in one episode of the series in 1979 playing Officer Manson who had the sole purpose of threatening to resign over the favourable treatment afforded prisoner Barbara Davidson in episode 17.
Split into simpler sentences: Prior to appearing as the character Myra Desmond in Prisoner, she took the role of a prison officer (Officer Manson), appearing in one episode of the series in 1979. This character had the sole purpose of threatening to resign over the favourable treatment afforded to prisoner Barbara Davidson in episode 17.