Chanfreau was born in Australia, but moved to France in 1968. Chanfreau made her first appearance in the Federation Cup for
Australia in
1966. She played for the
France Fed Cup team from 1969 to 1980. When Gail beat her sister
Carol Sherriff, who reached the third round of the Australian Open on five occasions, 8–10, 6–3, 6–3 in the
1966 Wimbledon Championships second round, that was the second match between sisters at Wimbledon, the first being in the
1884 Wimbledon Championships when
Maud Watson beat
Lillian. The next Wimbledon match between sisters was in
2000 between
Serena and
Venus Williams. Chanfreau reached the quarterfinals of the Australian Open in 1967 and 1972 as well as the quarterfinals of the French Open in 1968 and 1971. She won the French Open doubles in 1967, 1970 and 1971 with
Françoise Dürr and 1976 with
Fiorella Bonicelli. At the
Cincinnati Masters, she reached the singles final in 1969, losing to
Lesley Turner Bowrey. She was international veterans mixed-doubles champion in 1968 and 1975 with
Pierre Darmon. ==Personal life==