Question: Peter Sinfield was part of what rock group with fellow member Robert Fripp?

Context articles: Exposure (Robert Fripp album)
Red (King Crimson album)
Giles, Giles and Fripp
Works Volume 1
King Crimson
Gordon Haskell
The Land of Make Believe
Robert Fripp
Epitaph (song)
You and Your Heart So Blue

Exposure is the debut solo album by guitarist and composer Robert Fripp.
 Unique among Fripp solo projects for its focus on the pop song format, it grew out of his recent collaborations with David Bowie, Peter Gabriel, and Daryl Hall, and the latter two singers appear on the album.
 Released in 1979, it peaked at No. 79 on the "Billboard" Album Chart.
 Lyrics were mostly provided by Joanna Walton, a poet and girlfriend of Fripp.
Red is the seventh studio album by English progressive rock group King Crimson, released in 1974 by Island Records in the United Kingdom and by Atlantic Records in the United States.
 It was their last studio recording of the 1970s and the last before the lead member Robert Fripp temporarily disbanded the group.
 Though their lowest-charting album at the time, spending only one week in the UK charts, "Red" has received critical acclaim.
Giles, Giles and Fripp were an English rock group, formed in Bournemouth, Dorset in August 1967.
 It featured brothers Michael Giles on drums and vocals, Peter Giles on bass guitar and vocals, and Robert Fripp on guitar.
 The band's music showed an eclectic mix of Pop, Psychedelic rock, Folk, Jazz and Classical influences.
Works Volume 1, is the fifth studio album by the English progressive rock band Emerson, Lake & Palmer, released as a double album in March 1977 on Atlantic Records.
 Following their successful 1974 world tour, the group took a break from recording and touring.
 They relocated to Montreux, Switzerland and Paris, France to record a new album.
 Each member was allocated one side of a record to write and arrange their own tracks which were performed by the group.
 The fourth side features songs written by the entire group.
 Emerson wrote his Piano Concerto No. 1, Lake wrote several songs with Peter Sinfield, and Palmer picked tracks of varied styles.
King Crimson are an English rock band formed in London in 1968.
 The band has undergone numerous formations throughout its history of which 21 musicians have been members; since January 2017 it has consisted of Robert Fripp, Jakko Jakszyk, Tony Levin, Mel Collins, Pat Mastelotto, Gavin Harrison, Bill Rieflin and Jeremy Stacey.
 Fripp is the only consistent member of the group, and is considered the band's leader and driving force.
 The band has earned a large cult following.
 They were ranked No. 87 on VH1's "100 Greatest Artists of Hard Rock".
Gordon Haskell (born 27 April 1946, in Verwood, Dorset, England) is an English musician and songwriter.
 A pop, rock and blues vocalist, guitarist, and bassist, he was a school friend of King Crimson guitarist Robert Fripp, the two first working together in Fripp's mid-1960s teenage group The League of Gentlemen (not to be confused with Fripp's later new wave beat band).
 Haskell first gained recognition as bass player for the British band Les Fleur de Lys, and subsequently spent a short period in King Crimson, singing one of the songs on their second album and both singing and playing bass on their third album.
 After departing from King Crimson, he continued his musical career as a solo musician, finally gaining international recognition in 2001 with his hit song "How Wonderful You Are' 'followed by his Platinum selling album 'Harry's Bar'.
"The Land of Make Believe" is a 1981 single by British band Bucks Fizz.
 It reached No.1 in the UK in early 1982 - the second single by the band to do so.
 The song was produced by Andy Hill with music by Hill and lyrics by ex-King Crimson member Peter Sinfield.
 Despite the apparent sugar-coated style of the song, Sinfield later claimed it was a subtle attack on Margaret Thatcher and her government's policy at the time.
 "The Land of Make Believe" became a big hit across Europe in early 1982, topping the charts in Netherlands, Belgium and Ireland as well as the UK.
 The song was later covered by pop band allSTARS* for a 2002 single release.
Robert Fripp (born 16 May 1946) is an English guitarist, composer and record producer.
 As a guitarist for the progressive rock band King Crimson, Fripp has been the only member to have played in all of King Crimson's line-ups from their inception in the late 1960s to the present.
 He has also worked extensively as a studio musician, notably with singer David Bowie on the albums ""Heroes"" and "Scary Monsters (And Super Creeps)", Brian Eno, David Sylvian and contributed sounds to the Windows Vista operating system.
 His complete discography lists more than seven hundred releases over four decades.
"Epitaph" is the third track on British progressive rock band King Crimson's 1969 album "In the Court of the Crimson King".
 It was written by Robert Fripp, Ian McDonald, Greg Lake, and Michael Giles with lyrics written by Peter Sinfield.
"You and Your Heart So Blue" is a single by UK pop group Bucks Fizz.
 Released in June 1985, the song was written by Andy Hill and Peter Sinfield and was produced by Hill.
 This single was the last to feature member Jay Aston, who quit the group the same month.