Liberal Democrat peer and former MP for Christchurch Baroness Diana Maddock has died at the age of 75, after a short illness.
She won a spectacular victory in a by-election in Christchurch in 1993. She beat the Conservatives with one of the biggest swings in electoral history. She also served as Lib Dem president from 1998 to 2000.
Appointed to the Lords following her election defeat in 1997, she most recently acted as deputy chief whip for the party's group in the upper chamber.
Acting Lib Dem leader Sir Ed Davey said: "It is with great sadness that we have learned of the death of Diana Maddock.
"Diana helped shape the heart of the Liberal Democrat Party.
"Her warmth, expertise and leadership will be missed by all who knew her.
"Diana has been a great friend, support and inspiration to me over many years and I will miss her terribly.
"My thoughts and prayers are with her family at this time."
A former teacher, Baroness Maddock was elected to Southampton City Council in 1984 and became leader of the Liberal group.
Following the death of the incumbent Conservative MP Robert Adley, she successfully contested the seat of Christchurch in Dorset at the by-election in 1993.
During her time in the House of Commons, she drove through a private member's Bill which became the Home Energy Conservation Act 1995. The law placed a duty on councils to submit a report to government on the measures required to improve home energy efficiency by 30% over a 10-15 year period.
She is survived by her two daughters from her first marriage, Anna and Becki, along with husband and fellow peer Lord Alan Beith, formerly the MP for Berwick-upon-Tweed for more than 40 years.