Question: Name the English rock band formed in London who achieved international acclaim with their progressive and psychedelic music and who were a significant influence on the German progressive rock band Sylvan alongside Marillion and Genesis?
Context: Pink Floyd were an English rock band formed in London.  They achieved international acclaim with their progressive and psychedelic music.  Distinguished by their use of philosophical lyrics, sonic experimentation, extended compositions, and elaborate live shows, they are one of the most commercially successful and influential groups of popular music history. Silhouette is a progressive rock band from Utrecht, the Netherlands.  So far, the band has released four CD's.  The music they play is influenced by band such as Genesis, Pink Floyd, Marillion, but also by more recent music.  The Dutch Oor Pop Encyclopedie lists Silhouette under the category of progressive rock, other sources refer to their music as neo-progressive rock. Mach One are a British neo-progressive rock band, founded in 1980 by a group of students attending Burlington Danes High School in West London.  After a series of studio demos, school gigs and lineup changes, the band attracted the attention of Keith Goodwin (notable as publicist for Yes, Rod Argent, Black Sabbath, in the 1970s, and Marillion in the 1980s) who represented them through 1983-85.  During this time Mach One embarked on a series of live shows at pubs and clubs around London, and universities across England, while releasing two albums "Six of One" and "Lost for Words" that featured prominently in underground progressive rock fanzines (such as the Genesis Fanzine called "Afterglow") and specialist progressive rock catalogues.  However, in the more mainstream press they received mixed reviews for their second album, including a humorous 1-star review by Mary Anne Hobbs in Sounds (a British music paper), although their live show was given a positive write-up in the same paper a few weeks thereafter by journalist Gareth Thompson. Artificial Paradise is the third studio album by German progressive rock band Sylvan.  The eerie cover of a hand coming out of a craps table is indicative of the tone of the album itself, as the band has stated that overarching themes of the songs include "society's superficiality, deceitfulness and greed." Eloy is a German progressive rock band, whose musical style includes symphonic and space rock, the latter theme being more prevalent on earlier albums.  Despite their nationality and time period, the band is not generally considered krautrock because of their sound, which has much more in common with English progressive rock and symphonic rock groups such as Pink Floyd, King Crimson, Yes, and Camel. Sylvan is a German progressive rock band, with some hard rock moments, and some melodic pop-rock elements, showing influences of psychedelic rock, Pink Floyd, Marillion, and Genesis. Stupid Dream is the fifth studio album by British progressive rock band Porcupine Tree.  It was first released in March 1999, and then re-released on 15 May 2006 due to the band's rising popularity on major record label Lava Records with their releases of "In Absentia" in 2002 and "Deadwing" in 2005.  The album, along with "Lightbulb Sun" in 2000, represented a transitional period for the band, moving away from the band's earlier work in instrumental and psychedelic music, but before they took a more metal direction in 2002 onwards.  The album takes a commercially accessible pop rock sound while still retaining heavy progressive rock influences. Neal Morse (born August 2, 1960) is an American singer, multi-instrumentalist, bandleader and progressive rock composer based in Nashville, Tennessee.  In 1995, he formed the progressive rock band Spock's Beard with his brother Alan and released an album which was moderately successful.  In 1999, he joined former Dream Theater co-founder Mike Portnoy, Flower Kings' Roine Stolt and Marillion's Pete Trewavas to form the super-group Transatlantic.  In 2002, Neal Morse became a born again Christian, left Spock's Beard and began a Christian rock solo career, releasing many progressive rock concept albums about his new religious faith.  In the meantime, he continued to play with Transatlantic and formed three new bands, "Yellow Matter Custard", "Flying Colors" and "The Neal Morse Band". Clearlight is a French progressive rock band from the 1970s, although their best known work was produced in England, and released by a major British record company.  While progressive rock is an appropriate overall genre for the band, much of their work delves into other genres including psychedelic music, jam band music, symphonic rock, space rock, jazz fusion, and new-age music. Susumu Hirasawa (平沢 進 ) (born April 1, 1954) is a Japanese musician and composer.  In the fifth year of elementary school, Hirasawa took up the electric guitar, inspired by the surf and instrumental rock bands he heard on the radio and on TV, later joining his junior high school's band.  In 1973 he formed Mandrake, a progressive rock band that incorporated elements from heavy metal and krautrock.  Being one of the few Japanese progressive rock bands of its time, Mandrake achieved little success and released no albums during its lifetime.  After discovering punk rock and working on synthesizer-heavy projects, Hirasawa felt that progressive rock became just for entertainment and decided to reform the band as the electronic rock band P-Model in 1979.  Originally met with success, they turned to decidedly uncommercial post-punk and experimental rock after Hirasawa went through an averse reaction to his fame.  With Hirasawa at the forefront, the band went through various lineups and achieved some popularity in the Japanese independent music scene.
Answer: Pink Floyd