Lincolns Inn Fields WC2

Margaret MacDonald was a feminist who worked tirelessly for the rights of women at work, becoming a member of the Women's Industrial Council in 1894, where she conducted an enquiry into women's home work (a notoriously exploitative system) and championing training of women for skilled work. She set up the first trade schools for girls in 1904.
But, as ever, the main reason she is commemorated by this impressive seat in one of London's premier squares is that she was married to a famous and powerful man, viz Ramsay MacDonald, the first Labour prime minister.
She married MacDonald in 1896. By all accounts it was a happy union, resulting in six children, and MacDonald was devastated when she suddenly died in 1911 from blood poisoning - she was only 41.
Legend has it that Ramsay MacDonald designed her monument himself, for execution by the sculptor Richard Goulden, completed in 1914. It seems more likely that MacDonald gave Goulden a detailed brief rather than an actual design. It is a touching tribute to a wife and mother - make sure you read the bronze plate on the back of the stone seat.