Mary Elizabeth Truss (born 26 July 1975) is a British politician who was Prime Minister of the United Kingdom and Leader of the Conservative Party from September to October 2022. On her fiftieth day in office, she stepped down amid a government crisis, making her the shortest-serving prime minister in British history. The member of Parliament (MP) for South West Norfolk from 2010 to 2024, Truss held various Cabinet positions under three prime ministers—David Cameron, Theresa May and Boris Johnson—lastly as foreign secretary from 2021 to 2022.
Truss studied philosophy, politics and economics at Merton College, Oxford, and was the president of the Oxford University Liberal Democrats. In 1996, she joined the Conservative Party. She worked at Royal Dutch Shell and Cable & Wireless and was the deputy director of the think tank Reform. After two unsuccessful attempts to be elected to the House of Commons, she became the MP for South West Norfolk at the 2010 general election. As a backbencher, she called for reform in several policy areas including the economy, childcare and mathematics in education. Truss co-founded the Free Enterprise Group of Conservative MPs and wrote or co-wrote a number of papers and books, including After the Coalition and Britannia Unchained.