Sir Michael Tippett, 93, one of the leading figures of British music in the 20th century. His works included opera, choral and orchestral music, chamber and piano music, fused with strong rhythms and imaginative new sounds. His most famous work, the oratorio "A Child of Our Time," grew out of his outrage over the apathy toward the plight of Jewish refugees at the outbreak of World War II. In 1984, when he was 80, he premiered his Fourth Piano Sonata in Los Angeles for the Los Angeles Philharmonic Assn. On Thursday at his west London home of pneumonia.