Jethro Tull is a rock band that formed in Blackpool, England in the 1960s. Jethro Tull's music, though starting with blues rock with an experimental flavour, has incorporated elements of classical, Celtic folk music, and art rock. While other music groups did influence them in their early years, Jethro Tull quickly developed a unique, instantly recognisable sound. After an unsuccessful single, Jethro Tull released the bluesy album This Was in 1968. They released Stand Up in 1969, Jethro Tull's only UK number-one album. In 1970, Jethro Tull added keyboardist John Evan and released the album Benefit which has a continuity owing as much to studio technique as to compositional skill. Jethro Tull's best-known work, Aqualung, was released in 1971. After the 1992 tour, Anderson re-learned how to play the flute and began writing songs that heavily featured world music influences. 1995's Roots to Branches and 1999's J-Tull Dot Com are much less rock-based than Crest of a Knave or Catfish Rising. These most recent original Jethro Tull efforts reflect the musical influences of decades of performing all around the globe.