Largely neglected as a composer in his lifetime, he made an important contribution to the British piano repertoire and was influential in spreading knowledge of a wide range of mainly unfashionable music.
By the age of 15 his strong native urge to compose was interpreted by his father as a sign of mental illness and, finding a psychiatrist to endorse this view, he had his son committed to an asylum in Romford.
Later he did attend the Guildhall School of Music (1934), where he studied piano with Orlando Morgan, and the Royal College of Music (1943–45) in London on a part-time basis; at the latter he studied piano with Angus Morrison, horn with Frank Probin and received instruction in composition from Herbert Howells.
His advocacy of Granville Bantock, Havergal Brian, Dussek, Medtner, Hans Pfitzner, Max Reger, Franz Schmidt, Robert Volkmann and others was as sincere, and informed by an acquaintance with the music as close, as his discussions of Schubert's piano sonatas or Haydn's string quartets.
As a composer, Truscott perfected an expanded tonal idiom of contrapuntal intricacy and sometimes terse, no-nonsense expression, but a mystical streak sometimes emerges, as in the finale to his only completed Symphony, and his Elegy for string orchestra, composed in 1944 and never performed in his lifetime, is an utterance of astonishing romantic intensity.