Popular music of the United Kingdom in the 1970s built upon the new forms of music developed from blues rock towards the end of the 1960s, including folk rock and psychedelic rock.
 Several important and influential subgenres were created in Britain in this period, by pursuing the limitations of rock music, including British folk rock and glam rock, a process that reached its apogee in the development of progressive rock and one of the most enduring subgenres in heavy metal music.
 Britain also began to be increasingly influenced by aspects of World music, including Jamaican and Indian music, resulting in new music scenes and subgenres.
 In the middle years of the decade the influence of the pub rock and American punk rock movements led to the British intensification of punk, which swept away much of the existing landscape of popular music, replacing it with much more diverse new wave and post punk bands who mixed different forms of music and influences to dominate rock and pop music into the 1980s.
This is a list of rock music genres consisting of subgenres of popular music that have roots in 1940s' and 1950s' rock and roll, and which developed into a distinct identity as rock music in the 1960s, particularly in the United Kingdom and the United States.
 By the late 1960s, a number of identifiable rock music subgenres had emerged, including hybrids like blues rock, folk rock, country rock, and jazz-rock fusion, many of which contributed to the development of psychedelic rock influenced by the counter-cultural psychedelic scene.
 New genres that emerged from this scene included progressive rock, which extended the artistic elements; glam rock, which highlighted showmanship and visual style; and the diverse and enduring major subgenre of heavy metal, which emphasized volume, power, and speed.
 In the second half of the 1970s, punk rock both intensified and reacted against some of these trends to produce a raw, energetic form of music characterized by overt political and social critiques.
 Punk was an influence into the 1980s on the subsequent development of other subgenres, including new wave, post-punk and eventually the alternative rock movement.
 From the 1990s alternative rock began to dominate rock music and break through into the mainstream in the form of grunge, Britpop, and indie rock.
 Further fusion subgenres have since emerged as well as conscious attempts to revisit rock's history.
British folk rock (sometimes called electric folk) is a form of folk rock developed in the United Kingdom from the mid 1960s, and was at its most significant in the 1970s.
 Though the merging of folk and rock music came from several sources, it is widely regarded that the success of "The House of the Rising Sun" by British band the Animals in 1964 was a catalyst, prompting Bob Dylan to "go electric", in which, like the Animals, he brought folk and rock music together, from which other musicians followed.
 In the same year, the Beatles began incorporating overt folk influences into their music, most noticeably on the song "I'm a Loser" from their "Beatles for Sale" album.
 The Beatles and other British Invasion bands, in turn, influenced the Californian band the Byrds, who released their recording of Dylan's "Mr Tambourine Man" in April 1965, setting off the mid-1960s folk rock movement.
 A number of British groups, usually those associated with the British folk revival, moved into folk rock in the mid-1960s, including the Strawbs, Pentangle, Eclection, and Fairport Convention.
The folk music of England is traditionally based music, which has existed since the later medieval period.
 It is often contrasted with courtly, classical and later commercial music.
 Folk music has been preserved and transmitted orally, through print and later through recordings.
 The term is used to refer to English traditional music and music composed, or delivered, in a traditional style.
 English folk music has produced or contributed to several important musical genres, including sea shanties, jigs, hornpipes and dance music, such as that used for Morris dancing.
 It can be seen as having distinct regional and local variations in content and style, particularly in areas more removed from the cultural and political centres of the English state, as in Northumbria, or the West Country.
 Cultural interchange and processes of migration mean that English folk music, although in many ways distinctive, has particularly interacted with the music of Scotland.
 It has also interacted with other musical traditions, particularly classical and rock music, influencing musical styles and producing musical fusions, such as British folk rock, folk punk and folk metal.
 There remains a flourishing sub-culture of English folk music, which continues to influence other genres and occasionally to gain mainstream attention.
Indigo Girls are a Grammy Award-winning folk rock music American duo consisting of Amy Ray and Emily Saliers.
 They met in elementary school and began performing together as high school students in Decatur, Georgia, part of the Atlanta metropolitan area.
 They started performing with the name Indigo Girls as students at Emory University, performing weekly at The Dugout, a bar in Emory Village.
British popular music and popular music in general, can be defined in a number of ways, but is used here to describe music which is not part of the art/classical music or Church music traditions, including folk music, jazz, pop and rock music.
 These forms of music have particularly flourished in Britain, which, it has been argued, has influenced popular music disproportionately to its size, partly due to its linguistic and cultural links with many countries, particularly the former areas of British control such as United States, Canada, and Australia, but also a capacity for invention, innovation and fusion, which has led to the development of, or participation in, many of the major trends in popular music.
 This is particularly true since the early 1960s when the British Invasion led by The Beatles, helped to secure British performers a major place in development of pop and rock music, which has been revisited at various times, with genres originating in or being radically developed by British musicians, including: blues rock, heavy metal music, progressive rock, punk rock, British folk rock, folk punk, acid jazz, drum and bass, grime, dubstep and Britpop.
Sara Lee is an English bassist and singer-songwriter, who came to prominence replacing Dave Allen on bass guitar in post-punk band Gang of Four.
 She is also notable for work with Robert Fripp, B-52s, Ani DiFranco and Indigo Girls.
Folk rock is a music genre combining elements of folk music and rock music.
 In its earliest and narrowest sense, the term referred to a genre that arose in the United States and the United Kingdom around the mid-1960s.
 The genre emerged from bands such as the Beatles, the Searchers, and the Animals in the UK, and Bob Dylan and the Byrds in the US, who played traditional folk music and songs with rock instrumentation.
 The term "folk rock" is first noted as being used by the U.S. music press in June 1965 to describe the Byrds' music; the band's debut album was released the same month.
Medieval folk rock, medieval rock or medieval folk is a musical subgenre that emerged in the early 1970s in England and Germany which combined elements of early music with rock music.
 It grew out of the British folk rock and progressive folk movements of the later 1960s.
 Despite the name, the term was used indiscriminately to categorise performers who incorporated elements of medieval, renaissance and baroque music into their work and sometimes to describe groups who used few, or no, electric instruments.
 This subgenre reached its height towards the middle of the 1970s when it achieved some mainstream success in Britain, but within a few years most groups had either disbanded, or were absorbed into the wider movements of progressive folk and progressive rock.
 Nevertheless, the genre had a considerable impact within progressive rock where early music and medievalism in general, was a major influence and through that in the development of heavy metal.
 More recently medieval folk rock has revived in popularity along with other forms of medieval inspired music such as Dark Wave orientated neo-Medieval music and medieval metal.
Fairport Convention are a British folk rock band.
 Formed in 1967, they are widely regarded as a key group in the English folk rock movement.
 Their seminal album "Liege & Lief" is considered to have launched the British folk rock movement, which provided a distinctively English identity to rock music and helped awaken much wider interest in traditional music in general.
 The large number of personnel who have been part of the band are among the most highly regarded and influential musicians of their era and have gone on to participate in a large number of significant bands, or enjoyed important solo careers.

Question: Sara Lee has worked with which folk rock music duo?
Answer: Indigo Girls