Mother of Parliament

Mother of the House is an informal term for the most senior Member of a Parliament when that person is a woman. The term is equivalent to Father of the House, which is used to describe the longest continuously serving male member of the House of Commons in Westminster.

So far, no woman has been the longest-serving member of the House of Commons. The longest-continuously serving woman at Westminster is currently Harriet Harman, who has been an MP since 1982. Following the 2017 election, both Prime Minister Theresa May and Leader of the Opposition Jeremy Corbyn expressed the opinion that she should be known as the Mother of the House. Dame Margaret Beckett is the longest-serving woman to ever hold a seat in the House (in two separate tenures) since women first joined the House, but Harman has held the seat continuously since her first election.

If the current criteria for Father of the House are applied to women MPs, then the following would be the chronological sequence of the Mother of the House:

The term was used to describe Dr. Winnie Ewing at the first meeting of the Scottish Parliament in 1999. However, in accordance with the standing orders of the Scottish Parliament she was referred to as the "Oldest Qualified Member" in the Scottish Parliament Official Report.

...
Wikipedia