Blunt was the daughter and only child of Henry Wilfrid Blunt (born 17 May 1887, died 13 October 1956) and Maud Etta Hyde (born 1890, died 1976) who were married on 10 May 1915. She was the granddaughter of Sir John Harvey Blunt, eighth Baronet Blunt of London (born 1 January 1839, died 26 January 1922) and Susan Hoad (born 1843, died 1 April 1917).