In 1975 Margaret Thatcher, Conservative MP for Finchley, became the first woman to lead a western political party. The Conservative Party won the general election in May 1979 and Margaret Thatcher became the first female Prime Minister of the UK, continuing in the role until 1990.
In terms of women in the House of Commons more broadly, however, the number of women MPs fell to just 19 out of 635 following the 1979 election. They constituted 3% of the membership of the House, a decline from 4.3% at the previous general elections.