The British free improvisation scene originated in London and Sheffield during the mid 1960s. In groups such as AMM, the Spontaneous Music Ensemble and Joseph Holbrooke, a distinctive and ambitious musicality developed that still occupies most of its protagonists forty years later. Marked stylistic contrasts developed within the genre, notably the `atomistic' and `laminar' methods of interaction. Nonetheless, a consistency of principle and practice was also apparent that defined British free improvisation as unique. In some respects the genre resembled its German, Dutch and American counterparts, and also the jazz and classical avant-gardes that had inspired them. Both conceptually and practically, however, clear differences remained. The British free improvisers refined a method and an aesthetic of musical creativity, which suggested an intimate perspective and a detailed analysis of that which we accept as `music'. Its techniques and results were unconventional, but remained consistent with music's defining concepts and experiences. As such, British free improvisation suggested a more inclusive model of musicality than is common, and implied a broad critique of the cultural values that define `music' at all. Though the free improvisers themselves did not explicitly state the connection, their work may be viewed in the context of Deconstruction: the post-structuralist analytical strategy associated with philosopher Jacques Derrida. British free improvisation culminated from innovations within the twentieth century avant-garde. Referencing styles such as atonality and free jazz, it challenged the aesthetic, technical and hierarchical standards of Western tradition in a form that was striking and extreme, but also of logical development and focus. Free improvisation owed explicit debt to a variety of other musics; its most singular achievement however, was the redefinition of `rhythm' by which it disguised this fact. The music of the first generation British free improvisers is reliant upon precise conceptual and practical execution. But though this has enabled the genre to be musically innovative, in the long term it has also become a logical problem. With British free improvisation as its subject, the scrutiny of Deconstruction reveals significant discrepancies between what `free improvisation' implies and what it actually represents.