Who has been active for the longer period of time, The Bluebells or Gnarls Barkley?
The Bluebells: The Bluebells were a Scottish indie rock band, active between 1981 and 1986 (later briefly reforming in 1993, 2008–2009 and 2011). Gnarls Barkley:  They have released two studio albums, "St. Elsewhere" (2006) and "The Odd Couple" (2008).
The Bluebells