Ian Anderson's flute may be the defining factor in Jethro Tull's music, but it's only one element in a band that's been around since the late 60s. Originally a blues-based rock band with a few dollops of British folk in their sound, they evolved into one of the most popular progressive rock bands of the 70s. Jethro Tull formed in Blackpool, Lancashire, England in 1967. Their music is marked by the quirky vocal style and unique lead flute work of frontman Ian Anderson and by unusual and often complex song construction.