Margaret Thatcher becomes Britain's first female prime minister

On the afternoon of May 4, 1979, Margaret Thatcher was summoned to Buckingham Palace, accepted Queen Elizabeth II’s invitation to form a government, and became the first woman to serve as Prime Minister of the United Kingdom.

The Oxford-trained chemist and barrister took office the day after her Conservative Party won a 44-seat majority over James Callaghan’s Labour government. Her arrival was a global first too: only a handful of nations — among them Sri Lanka, India, and Israel — had previously had a woman lead their government.

She would hold the office for nearly 12 years, the longest continuous premiership of the 20th century.

Known as the “Iron Lady,” Thatcher reshaped Britain’s economy and politics across the 1980s, leaving a divisive legacy that is still argued over today. She remained in Downing Street until 1990.