Task: Question Answering
Input (English): Passage: Descriptions of Imogen as a small child indicate that she had blue eyes, fair hair, an oval face reminiscent of her father's, and a rather prominent nose inherited from her mother.  In 1912, at the age of five, she joined the kindergarten class at the Froebel Institute, and remained at the school for five years. Summers were often spent at the Holsts' rented country cottage at Thaxted in Essex, where Gustav Holst began an annual Whitsun Festival in 1916.In 1917 Imogen began boarding at Eothen, a small, private school for girls in Caterham, where Jane Joseph, Gustav's star pupil from SPGS, taught music.  A letter home, dated 17 July 1917, tells of "compertishions [sic], and ripping prizes, and strawberries and cream for tea".  At the school, Imogen studied piano with Eleanor Shuttleworth, violin with André Mangeot (described as "topping") and theory with Jane Joseph ("ripping"). Under Joseph's tuition Imogen produced her first compositions—two instrumental pieces and four Christmas carol tunes—which she numbered as Ops. 1, 2, and 3. In the summer term of 1920, she composed and choreographed a "Dance of the Nymphs and Shepherds", which was performed at the school under her direction on 9 July.Imogen left Eothen in December 1920 hoping to study under Ruby Ginner at the Ginner-Mawer School of Dance and Drama, but was rejected on health grounds, although there appeared to be no significant medical issue. She then studied at home under a governess, while waiting to start at St Paul's Girls School in the autumn. At Whitsun 1921 she took part as a dancer in her father's production of Purcell's semi-opera from 1690, Masque of Dioclesian, held in the St Paul's School grounds and repeated a week later in Hyde Park.In September 1921 Imogen began at St Paul's Girls School, and became a boarder from Spring 1922. In July 1922 she performed a Bach Prelude and Fugue on the piano, for which Joseph praised her warmly, writing: "I think everyone enjoyed the Bach from beginning to end, they all made nice contented noises at the end of it".  Imogen's SPGS years were generally happy and successful. In July 1923 she won the junior Alice Lupton piano prize, but her chances of distinction as a pianist were marred when she began to develop phlebitis in her left arm. Among other activities she became interested in folk music and dance, and in 1923 became a member of the English Folk Dance Society (EFDS).  In 1924–25, her final year at SPGS, Imogen founded a folk dance society in the school. At an end-of-term school concert late in July 1925, she played Chopin's étude in E major and gave the first performance of Gustav Holst's Toccata. 
Question: What is the name of the person who took part as a dancer in her father's production of Purcell's semi-opera from 1690, Masque of Dioclesian?
Output (English): Imogen.