Born and raised in West Germany, she has lived in the UK since 1974.
Stuart was Chair of the Vote Leave Campaign Committee and was one of its most high-profile figures, along with the Conservative MPs Boris Johnson and Michael Gove.
The Vote Leave campaign was successful in achieving its goal at the 2016 United Kingdom European Union membership referendum of winning a majority of votes for Leave.
Since September 2016, Stuart has served as Chair of Vote Leave's successor organisation, Change Britain.
Since 2015, she has been a Steering Committee member of the Constitution Reform Think Tank, chaired by Robert Gascoyne-Cecil, 7th Marquess of Salisbury, which seeks a new constitutional settlement in the UK.
Their advocacy resulted in a proposal for a new UK law being created - Act of Union.Stuart did not run for reelection in the 2017 general election.
After she left Parliament, she was appointed by the Conservative government as Chair of Wilton Park, an executive agency of the UK Foreign Office dedicated to conflict resolution in international relations, in October 2018.