Jethro Tull married British blues and folk music into a popular rock flavour, but like most UK bands of the late 1960s and 70s, they ditched the blues for a harder-sounding guitar and, in Jethro Tull's case, a prominent flute, on-stage theatrics, and album-length concept songs like "Thick as a Brick".
Fife-born Ian Anderson started playing in bluesy-rock bands in the mid-60s, and eventually one of these bands morphed into Jethro Tull. Throughout a long career Jethro Tull has had many line-up changes, with Anderson the sole survivor from the beginning. Their second LP Stand Up topped the British album charts in 1969, and thanks to its creative integration of Celtic folk and classical flourishes into rock, Stand Up can be seen as an important step between blues-rock and prog-rock. Jethro Tull's most famous moment came with their fourth album, 1971's Aqualung, and they followed that up with the concept album Thick as a Brick (1972), their first real prog record. Their popularity rocketed and their massive tours became more indulgent and theatrical, as Jethro Tull became one of the biggest prog-rock bands in the world. But the punk revolution took the wind from their sails, and Jethro Tull struggled to remain relevant as prog became a dirty word. Still, they had won enough loyal fans during their peak to continue to sell well through the 1980s, and they even managed to win a Grammy in 1989 for Best Hard Rock/Metal Performance (despite being a few steps away from a hard rock or metal band). The band continues to tour today.
