This volume serves as a critical supplement to the original survey, aiming to document the evolution and expansion of chamber music repertoire and composition from 1929 through the mid-20th century. Colin Mason, a noted musicologist, compiles this update to bridge the gap between the foundational 1929 text and the contemporary musical landscape. The work utilizes a systematic, encyclopedic approach to categorize composers, regional developments, and stylistic shifts that occurred in the decades following the initial publication.

Experts and music historians regard this supplement as a vital component of the broader Cobbett reference set for understanding 20th-century chamber music. Readers frequently note the academic density of the prose, which is tailored for researchers and serious students of musicology.