which includes some work they composed together some years before. In 2003, Sherwood released The Unknown, another album with Chris Squire as Conspiracy. More recently, Sherwood has been working on further tribute albums, notably Back Against the Wall and Return to the Dark Side of the Moon, tributes to Pink Floyd's The Wall and The Dark Side of the Moon respectively. The latter includes a new track recorded with Tony Kaye. Circa and Yoso In 2007, a new band with Sherwood, Alan White, Tony Kaye and Jimmy Haun was announced, called Circa. With the release of their debut album Circa 2007 and a live DVD concert, Circa has played various live dates. White left the band and was replaced by Jay Schellen. On January 14, 2009, Circa self-released on the Internet its second studio album, Circa HQ. This time, White was not available due to his commitments with Yes (who had begun a new tour). Sherwood's long time friend, collaborator and drummer, Jay Schellen, replaced White on the album. After a short international tour, Sherwood and co. started another project with former Toto singer, Bobby Kimball. Kimball, Sherwood, Tony Kaye and Jimmy Haun formed new band, Yoso, with a debut studio album in April 2009. Haun later abandoned the line-up (in order to focus on his work for adverts). He was replaced by Yes tribute band guitarist, Johnny Bruhns. Schellen chose to focus on his work in Asia Featuring John Payne and, after a number of other drummers, the band toured with Scott Connor on drums. Yoso then disbanded. In 2011, Circa returned with a new line-up of Sherwood, Kaye, Bruhns and Connor, while Sherwood released his fifth solo album, What was the Question?. In 2012, Sherwood wrote, produced, arranged and performed on The Prog Collective, an album featuring vocal or instrumental contributions from many of the progressive rock artists he had worked with over the years. He reprised the concept with a similar collection of artists for Epilogue, released in 2013. On October 8, 2013, they released the official video to William Shatner's record Ponder The Mystery, followed by a sold-out tour with Circa. Ponder The Mystery also features appearances of Steve Vai, Robby Krieger, Al Di Meola, George Duke, Vince Gill, Dave Koz, Rick Wakeman and Edgar Winter. On July 8, 2016, Sherwood re-grouped with Circa to release their fourth album titled Valley Of The Windmill. Other projects