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. Royal College of Music Although destined like her father for the RCM, Holst first spent a year studying composition with Herbert Howells, piano with Adine O'Neill and the French horn with Adolph Borsdorf, while participating in the EFDS summer schools and other musical activities. In July 1926 she arranged and conducted the music for an EFDS pageant, held at Thaxted as a fund-raiser towards the building of the society's new headquarters at Regent's Park. Holst began at the RCM in September 1926, studying piano with Kathleen Long, composition with George Dyson, and conducting under W. H. Reed. Her aptitude as a conductor was evident in December 1926, when she led the college's Third Orchestra in the opening movement of Mozart's "Prague" Symphony. This and other performances on the podium led The Daily Telegraph to speculate that Holst might eventually become the first woman to "establish a secure tenure of the conductor's platform".