Benning was born in Urmston, Lancashire, England. In 1971, as Christine Tranter, she won the AAAs Under 17 800 metres title. In 1974, still a teenager, she was 15th at the World Cross Country Championships and won a gold medal in the team event. In 1975, she was 18th. She finished fifth in the 1500 m final at the 1977 World Student Games (Universiade) in Sofia in 4:09.7.