His teaching style is a source of controversy among some of his former students, who considered it to be dogmatically authoritarian. One of Segovia's most celebrated former students of the classical guitar, John Williams, has said that Segovia bullied students into playing only his style, stifling the development of their own styles. Williams has also said that Segovia was dismissive of music that did not have what Segovia considered the right classical origins, such as South American music with popular roots. He was also critical of Williams' work with the group Sky for the same reasons.