Question: What "Virtual Choir" producer worked with British composer Guy Sigsworth? 

Context articles: Eric Whitacre
Guardian (song)
Lux Aurumque
Nothing Fails
What It Feels Like for a Girl
Jem (singer)
Lens (song)
Acacia (band)
Cradle (album)
Guy Sigsworth

Eric Edward Whitacre (born January2, 1970) is a Grammy-winning American composer, conductor, and speaker, known for his choral, orchestral and wind ensemble music.
 He is also known for his "Virtual Choir" projects, bringing individual voices from around the globe together into an online choir.
 In March2016, he was appointed as Los Angeles Master Chorale's first artist-in-residence at the Walt Disney Concert Hall.
"Guardian" is a song by Canadian-American recording artist Alanis Morissette, released as the lead single from her eighth studio album, "Havoc and Bright Lights" (2012).
 The song was written by Morissette and Guy Sigsworth, and produced by Sigsworth and Joe Chiccarelli.
 It is a rock song, where Morissette promises to look after a special someone.
Lux Aurumque ("Light and Gold", sometimes "Light of Gold") is a choral composition in one movement by Eric Whitacre.
 It is a Christmas piece based on a Latin poem of the same name, which translates as "Light, warm and heavy as pure gold, and the angels sing softly to the new born baby".
 In 2000, Whitacre set a short Latin text for mixed choir a cappella.
 In 2005, he wrote an arrangement for wind ensemble.
 The choral version became known through Whitacre's project Virtual Choir in 2009.
 The piece is also available for men's choir.
 A performance takes about four minutes.
"Nothing Fails" is a song by American singer-songwriter Madonna from her ninth studio album, "American Life" (2003).
 Written by Madonna, Guy Sigsworth and Jem Griffiths, and produced by the singer along with Mirwais Ahmadzaï and Mark "Spike" Stent, it was released as the third single from the album on October 26, 2003.
 Originally titled "Silly Thing", "Nothing Fails" is a love song which has acoustic guitar chords and a gospel choir appearance.
 Lyrically, the song discusses a lover who is the one, and how their meeting was not just chance.
 A number of remixes of the song were done, with one of them being included on Madonna's remix album "Remixed & Revisited" (2003).
"What It Feels Like for a Girl" is a song by American singer-songwriter Madonna recorded for her eighth studio album "Music" (2000).
 It was released as the third single from the album on April 17, 2001 by Maverick Records, with two other versions being also released: a dance-remix produced by Above & Beyond and a Spanish version titled "Lo Que Siente La Mujer".
 It was written by Madonna, Guy Sigsworth and David Torn, while production was done by Madonna, Sigsworth and Mark Stent.
 "What It Feels Like For a Girl" is a mid-tempo electronic and synthpop song, with filtered bass licks, tidal keys and pads as part of its instrumentation.
 Lyrically, it conveys society's double standard toward women, addressing hurtful myths about female inferiority.
 To emphasize the message, the song opens with a spoken word sample of Charlotte Gainsbourg from the 1993 film "The Cement Garden".
Jemma Griffiths (born 18 May 1975), known by her stage name Jem, is a Welsh singer, songwriter, and record producer.
 Born and raised in Penarth, Wales, she began songwriting at an early age.
 After graduating university in 1996 she worked as a DJ as well as co-founder of record label Marine Parade in Brighton.
 By 2002 she was focused heavily on writing and singing her own songs, collaborating with various producers in the United States such as Guy Sigsworth, Yoad Nevo, and Ge-Ology to help create what would become her debut studio album: "Finally Woken", released on 24 March 2004 through ATO Records.
 Popularised by singles "They", "Just a Ride" and "Wish I", the album garnered generous sales and chart performance in the United States, Canada, Japan and Europe.
 Jem followed up her successful debut with her second album, "Down to Earth", released on 18 September 2008.
 Jem's musical style is varied and encompasses genres of trip hop, electronica, pop rock and new wave, with critics often associating her with other female British musicians Dido, and Beth Orton.
"Lens" is a song by Canadian-American recording artist Alanis Morissette, released as the second single from her eighth studio album, "Havoc and Bright Lights".
 The song was written by Morissette and Guy Sigsworth, and produced by Sigsworth and Joe Chiccarelli.
 The song was played at most shows of Guardian Angel Tour.
Acacia was a multi-cultural British experimental pop band active during the mid-1990s.
 The band is most notable for helping to launch the subsequent musical careers of several of its members, most notably keyboard player/producer Guy Sigsworth, singer Alexander "Blackmoth" Nilere and associate vocalist Imogen Heap (later a solo artist, half of Frou Frou and a collaborator with Urban Species and Jeff Beck).
 Though never commercially successful, Acacia attracted a good deal of underground attention during their existence and were notable for their eclectic musical approach and for Nilere's unorthodox, polysexual image.
Cradle is the only album by the English pop group Acacia, which featured future record producer Guy Sigsworth (Madonna, Alanis Morissette, others) and singer Alexander "Blackmoth" Nilere.
 It is notable for being the first full album released by Sigsworth as both full group member and producer (following his work as keyboard player with Björk and Seal) and for being the first record to heavily feature later solo artist Imogen Heap (who performs on all but one track).
Guy Sigsworth is a British composer, producer and songwriter.
 During his career he has worked with many artists, including Seal, Björk, Goldie, Madonna, Britney Spears, Kate Havnevik, Imogen Heap, Bebel Gilberto, Mozez, David Sylvian, Alanis Morissette, Eric Whitacre and Alison Moyet.
 He has also collaborated with many celebrated instrumental musicians, including Talvin Singh, Jon Hassell and Lester Bowie.
 He was previously a member of the band Frou Frou together with Imogen Heap.