After appearing in the 25 episodes that made up the four stories of the seventh season, John left the programme because she was pregnant with her first child, and new producer Barry Letts had already decided against renewing her contract. Letts and script editor Terrance Dicks viewed the character as unsuccessful, feeling that she did not fill the companion's role of asking the Doctor for exposition and acting as an audience surrogate. In 1978, John expressed mixed feelings about her role as Liz, saying, "I was excited at first to be a brainy girl, but all the directors wanted really was a sexy piece. It was such an effort looking glamorous on cold clay-pits and rubbish dumps. I enjoyed the series but found it restricting after a while." John continued to appear at fan conventions from the 1990s onwards.