He was born in Oxford where he was a classics scholar before studying—somewhat hesitantly—with John Ireland at the Royal College of Music in London, after which he went to Vienna on a six month scholarship to become a private pupil of Anton Webern, which became decisive in his composition career.
Searle was one of the foremost pioneers of serial music in the United Kingdom, and used his role as a producer at the BBC from 1946 to 1948 to promote it. He was General Secretary of the International Society for Contemporary Music from 1947 to 1949. He accepted this post with the encouragement of the new president, Edward Clark. For Clark, he composed the Quartet for Clarinet, Bassoon, Violin and Viola, Op. 12, a musical palindrome.
Searle wrote his Piano Sonata, Op. 21 for a recital at the Wigmore Hall on 22 October 1951, given by the Australian pianist Gordon Watson to celebrate the 140th anniversary of the birth of Franz Liszt. (Watson also performed the complete Transcendental Études on that occasion.) The Sonata was loosely based on Liszt's Sonata in B minor and has been described as "probably, both the finest and most original piano work ever produced by a British composer".
Searle wrote the monographs Twentieth Century Counterpoint and The Music of Franz Liszt. He also developed the most authoritative catalogue of Liszt's works, which are frequently identified using Searle's numbering system.
Howard, Leslie; Short, Michael; Searle, Humphrey; Winklhofer, Sharon (2004). Ferenc Liszt (1811-1886) : list of works : comprehensively expanded from the catalogue of Humphrey Searle as revised by Sharon Winklhofer = elenco delle opere : ampliamento del catalogo di Humphrey Searle nella revisione di Sharon Winklkofer. Milano : Rugginenti Editore. ISBN 887665433X.
Searle, Humphrey (1954). The Music of Liszt. London: Williams & Norgate.
Searle, Humphrey (1954). Twentieth Century Counterpoint. London: Williams & Norgate.