Rachel (Ray) Costelloe was born in London on 4th June 1887. She attended Kensington High School before studying mathematics at Newnham College (1905-1908). While at the University of Cambridge she was an active member of Cambridge University Women's Suffrage Society.
After leaving university she became secretary of the West of England Women's Suffrage Society. In 1911 she married Oliver Strachey. Over the next few years they had two children, Christopher and Barbara.
In 1913 Ray Strachey was elected chairman of the London Society for Women's Suffrage. In 1916 she was honorary parliamentary secretary of the National Union of Women's Suffrage Societies responsible for supervising the passage of the Qualification of Women Act. At the 1918 General Election she stood unsuccessfully for the House of Commons. Later she worked as political secretary to Nancy Astor, the first female MP.
In 1921 Strachey built a house in Fernhurst. The author, Helena Wojtczak, has pointed out: "She bought nine acres of land and built a house of pisé de terre (rammed earth). She named it Copse Cottage but it is known to this day as the Mud House. She installed an 80ft x 30ft pool (where she swam in the nude), and acquired WLA clothing - corduroy breeches, boots and a straw hat - to wear around her estate." Virginia Woolf was a frequent visitor.
After the First World War she was the editor of The Common Cause and then of its successor, The Women's Leader. Ray Strachey was also the author of Women's Suffrage and Women's Service (1928), The Cause: A Short History of the Women's Movement in Great Britain (1928) and Millicent Garrett Fawcett (1931).
In 1935 Strachey was appointed as head of the Women's Employment Federation and subsequently published Career Openings for Women (1935).
Ray Strachey died on 16th July 1940 in the Royal Free Hospital of heart failure, following an operation to remove a fibroid tumour.