Question: Untitled (or box set) is a box set compilation of songs released by which British musician, songwriter, and producer under the pseudonym Bass Communion, which English musician and record producer, most associated with the progressive rock genre?

Context articles: Bass Communion I
Bass Communion II
Untitled (Bass Communion Box)
Molotov and Haze
Chiaroscuro (Bass Communion album)
Bass Communion III
Boîte à Bonbons
Trash Box
Steven Wilson
Indicates Void

I (or Bass Communion I) is the name of the first studio album released by British musician, songwriter, and producer Steven Wilson under the pseudonym Bass Communion in 1998.
 It was reissued in December 2001 through Hidden Art record label.
II (or Bass Communion II) is the name of the second studio album released in 1999 by British musician, songwriter, and producer Steven Wilson under the pseudonym Bass Communion.
Untitled (or box set) is a box set compilation of songs released by British musician, songwriter, and producer Steven Wilson under the pseudonym Bass Communion.
 It contains many rarities from the last 15 years of Steven's ambient and drone work, especially from vinyl only editions of Bass Communion albums.
 It also features the previously unreleased track "Temporal", recorded in 2012 as a homage to composer Harrison Birtwistle and his 1971 composition "Chronometer" – both pieces are created entirely from the sounds of clocks and other timekeeping devices.
Molotov and Haze is the eighth studio album released by British musician, songwriter and producer Steven Wilson under the pseudonym Bass Communion.
Chiaroscuro is a live album by British musician, songwriter and producer Steven Wilson under the pseudonym Bass Communion.
 The title track was recorded live in Antwerp in November 2008.
 The second track, Fusilier also appears on the Bass Communion / Fear Falls Burning split 7" LP given away to attendees of the concert.
III (Bass Communion III or Bass Communion CDR) is the name of the third studio album released by British musician, songwriter, and producer Steven Wilson under the pseudonym Bass Communion.
 It is a compilation of leftover pieces recorded between 1995-1999 that were not included on either of the previous two Bass Communion albums.
 In 2008, the album was re-issued together with II in a 2-CD edition limited to 1,200 copies.
Boîte à Bonbons ("Box of Candies") is a 16-CD box set compilation of the recorded songs of Jacques Brel.
 The limited edition box set was released to mark the 25th anniversary of Jacques Brel's death.
 The box set includes 15 albums remastered from the original records.
 CD digipacks are presented in their original sleeve with lyrics.
 The box set also includes an illustrated booklet with various pictures, a biography, and Brel's citations and testimonies.
 Also included are five never before released songs from the recording sessions of the album "Les Marquises".
 Included with the booklet is a bonus CD containing 28 titles: 26 songs from Radio Hasselt recorded 14 and 21 August 1953, a recording from the Brel family's private collection, and a 1962 recording from the Dutch television show AVRO.
 The box set is also available in an alternate velvet box format with CDs in crystal cases.
Trash Box is a 5-CD box set of mid-1960s garage rock and psychedelic rock recordings, primarily by American bands.
 This box set is similar to the earlier "Pebbles Box" (a 5-LP box set) and includes almost all of the same recordings in that box set (and in the same order), along with numerous bonus tracks at the end of each disc.
 Supposedly, "the Trash Box" collects the first five volumes of the CDs in the Pebbles series (i.e., those released by AIP Records, not to be confused with the 4 earlier CDs that were issued by ESD Records).
 However, as is generally true of the CD reissues of these five volumes (though not nearly to the same extent), the tracks differ significantly on all five discs as compared to both the original Pebbles LPs and the later Pebbles CDs in the corresponding volumes; and the surf rock rarities on "Pebbles, Volume 4" have been eschewed entirely.
 Overall, there are 109 tracks in the box set (excluding the introduction and ending cuts) as compared to 101 songs on the individual CDs and 72 tracks in the "Pebbles Box".
 Although most of the recordings on "the Trash Box" were released at some point on one of the individual Pebbles albums, several of the songs have not appeared elsewhere in the Pebbles series.
 Inexplicably, one of these songs is the well-known hit "I Fought the Law (but the Law Won)" by the Bobby Fuller Four (on Disc Four) – which is also included in the "Pebbles Box" – in place of the much rarer "Wine Wine Wine" by Bobby Fuller that appears on "Pebbles, Volume 2".
Steven John Wilson (born 3 November 1967) is an English musician and record producer, most associated with the progressive rock genre.
 Currently a solo artist, he became known as the founder, lead guitarist, singer, and songwriter of the band Porcupine Tree, as well as being a member of several other bands.
 He has also worked with artists such as Opeth, King Crimson, Pendulum, Jethro Tull, XTC, Yes, Marillion, Tears for Fears, Roxy Music, and Anathema.
Indicates Void is the name of the fifth studio album released by British musician, songwriter and producer Steven Wilson under the pseudonym Bass Communion, and was limited to 300 12-inch LP copies in handmade sleeves, 100 copies in a silver sleeve, 100 copies in a gold sleeve, and 100 copies as part of a box set of the first 3 "C" releases.