The progressive rock genre spawned many groups that became top-grossing arena acts -- Pink Floyd and Genesis are two -- as well as many who progressed right into obscurity. Henry Cow were one of the best known and most widely traveled English bands of the progressive era (though only a cult favorite in the U.S. and actually more popular in Continental Europe than in their home country), and their music has aged amazingly well over the ensuing decades due to the group's diverse influences (Oliver Messiaen, Kurt Weill, Frank Zappa, and Soft Machine were a few) and uncompromising creativity. Henry Cow functioned more or less as a collective, with a true group identity that changed from album to album as members came and went. This turnover was one factor in their consistent vitality; another was the dedicated core of the band, a serious, politicized trio whose interest in improvisation served to leaven the complexity they supplied as primary writers.
