Baroness (Diana) Maddock served as Liberal Democrat MP for Christchurch between 1993 and 1997, acting as the Party's Spokesperson on Housing, Women's Issues and Family Policy. She successfully sponsored the Home Energy Conservation Act 1995 as a Private Member's Bill.

She was created a Baroness, taking a seat in the House of Lords following the 1997 General Election, and was the Liberal Democrat frontbench Spokesperson on Housing until November 2004. From 1998-2000 she was Federal President of the Liberal Democrats. Outside Parliament, she holds the posts of President of the National Housing Forum and Vice President of the National Housing Federation, the Richard Newitt Trust and the Wessex Medical Trust. She is a patron of the Westminster Forum.

Baroness Maddock continues to take an interest in energy efficiency and recently saw Brian White MP's Private Member's Bill through the House of Lords to become the Sustainable Energy Act.