Philip Heseltine was a British composer and music writer. He used the pen name Peter Warlock for his music, partly because he was interested in old stories and the supernatural. Today he is best known for writing beautiful songs for singers.

As a boy at Eton College, Heseltine became friends with the composer Frederick Delius, who inspired him to write music. He tried studying at Oxford and in London, but he did not enjoy university life. Instead, he became a music critic, writing strong opinions in newspapers and magazines. He also loved folk songs and very old English music, and he helped bring this early music back into fashion.

After living in Ireland, Wales, and Kent, he wrote most of his best work in the 1920s, including song cycles such as The Curlew and the Capriol Suite. People admired his talent, but his lifestyle was wild and sometimes shocking.

Near the end of his life, he felt deeply unhappy and stopped composing. In 1930, he died from coal gas poisoning.