Born at Denham, Buckinghamshire, she was the second daughter and the youngest of three children of Commander Harold William Swithinbank, DL (1858 – 1928), a landowner of Denham Court, and his wife, Amy, the daughter of James Crossley Eno, inventor of Eno fruit salts. Through her grandfather Admiral George Winthrop she was descendant from the Winthrop family of New England in British North America. She was educated privately and at the Heathfield School, near Ascot.
Swithinbank met Stafford Cripps in January 1910. His father, Charles Cripps, was standing in the Conservative interest for Wycombe, with Stafford supporting his father's candidature; among the campaign helpers was Isobel. The pair corresponded and she visited the Cripps home at Parmoor. The following year, both were members of a family party which went to the winter sports in Switzerland and they soon became engaged. The couple married on 12 July 1911 at Denham parish church.
They had four children:
- Sir John Stafford Cripps (1912–1993)
- Isobel Diana Cripps (1913–1985)
- (Anne) Theresa Cripps (1919–1998), who was married to Sir Robert Cornwallis Gerald St. Leger Ricketts, 7th Bt.
- Peggy Cripps, born Enid Margaret Cripps (1921–2006), children's author and philanthropist, who married the Ghanaian lawyer and statesman Joe Appiah; their son is the philosopher Kwame Anthony Appiah (b. 1954).
International interests and affiliations
During World War II, Lady Cripps was president of the British United Aid to China Fund, and in June 1946, was appointed a GBE for her public services. Later that year, she undertook an extensive tour of China where she was the guest of General and Madame Chiang Kai-shek. During her tour, she was invited by Mao Zedong to visit Yenan and was welcomed on her arrival by Madame Jiang. She was later Chairwoman of the Sino-British Fellowship Trust for some years. Following the marriage of her daughter, Peggy, to Joe Appiah, Lady Cripps developed an interest in affairs in Ghana and visited Appiah in Accra when he was being held under a preventive detention order.
In addition to her appointment as a GBE, she was also appointed a Special Grand Cordon of the Order of the Brilliant Star, first class. In 1946 she was given the award of the National Committee of India in celebration of International Women's Year.
- Howard, Joseph. Visitation of England and Wales, Volume 7. England, 1899, pages 150-151.
- Stark, James. The loyalists of Massachusetts and the other side of the American Revolution. Boston, 1910, pages 426-429.
- Brozan, Nadine (16 February 2006) "Peggy Appiah, 84, Author Who Bridged Two Cultures, Dies". The New York Times
- "The Bulletin of the Pioneer Health Centre". Peckham. 1 (5). September 1949. Retrieved 21 October 2016.