First female judge in Scotland. Born in Glasgow, Cosgrove was educated at Glasgow High School for Girls and the University of Glasgow. She became an advocate in 1968 and was appointed a Queen's Counsel in 1991.
Appointed the first female Sheriff of Glasgow & Strathkelvin in 1979, Cosgrove went on to become Sheriff of Lothian & Borders (1983-96). In 1992, she was made a temporary judge in the High Court and Court of Session and her historic permanent appointment came in 1996. She has also served as Chairman of the Mental Welfare Commission for Scotland (1991-6) and was appointed Deputy Chairman of the Boundary Commission for Scotland in 1997.
Cosgrove was awarded an honorary degree from Napier University in 1997 and received an OBE in 2004 for services to the criminal justice system in Scotland.