Mark Clarke (born July 25, 1950, in Liverpool, England)is a former member of Colosseum and Uriah Heep. He was bass guitarist for Colosseum from 1970 until 1972 (and 1994 for Colosseum's reunion), when he joined Uriah Heep, performing (and co-writing) on just one studio track "The Wizard" on their 1972 album Demons & Wizards. Mark has also played bass on Ken Hensley's solo albums. Colosseum is a British jazz-rock band considered also a part of the early roots of progressive rock. ... Uriah Heep is a British rock band, officially formed in 1969 in England, when record producer Gerry Bron invited keyboardist Ken Hensley (previously a member of The Gods and Toe Fat) to join Spice, a band signed to his own Bronze Records label. ... Demons & Wizards is the fourth album released by British rock band Uriah Heep. ... Ken Hensley (born Kenneth Hensley, on 24 August, 1945, in Hertfordshire, England) is a keyboard (especially Hammond organ) player, guitarist, singer, songwriter and producer best known for his work with Uriah Heep during the 1970s. ...