When women finally won the right in 1918 to enter Britain’s Parliament, many expected the first female lawmaker to sit there to come from the ranks of the suffragists, the activists who had fought, often at huge personal cost, for the vote.

Instead, it was someone of wealth and privilege, a well-connected socialite, and an American.

A century after she was elected to Parliament, the achievements of Nancy Astor have been celebrated at several events, including one in Plymouth, the city she represented, where a statue of her was unveiled by Theresa May, one of two women to have been prime minister.

Yet while Lady Astor was a trailblazing feminist, her political reputation was marred by anti-Semitism and by support for the appeasement of Adolf Hitler in the 1930s, leaving historians divided over her legacy.

In terms of advancing equality, Jacqui Turner, an associate professor at the University of Reading, sees Lady Astor as a pioneer and someone of extraordinary resilience.

“She opened the door,” Dr. Turner said. “If she had given up or said, ‘This is too hard,’ she would have set back the cause by a decade at least.”