Lady Theresa May served as the prime minister of the United Kingdom from 2016 to 2019 — the second woman ever to hold the office. Her premiership marked the culmination of 21 years of continuous service in Parliament, having held a total of 14 ministerial or shadow ministerial posts, serving as the first female chairman of the Conservative Party and the longest-serving Conservative home secretary in more than a century.

In her time as prime minister, May led the UK through some of the of the most consequential events in Britain’s recent geopolitical history. Her tenure included a commitment to net-zero greenhouse gas emissions by 2050, making the UK the first major global economy to set such a goal; delivery of the formal notification of the UK’s intention to leave the European Union; the establishment of the British Government’s Race Disparity Unit to examine the treatment of people with different backgrounds across public services, in the workplace, and the criminal justice system; and the coordination of responses to multiple incidents of international and domestic terrorism on British soil, including a March 2018 use of a chemical nerve agent for which there was evidence of Russian state culpability.