While it was little-known outside of the U.K., Pub Rock essentially gave rise to Punk rock in the early to mid-1970s. Pub Rock pioneered a do-it-yourself ethos and held to an unpretentious attitude about making music. Like Punk a few years later, Pub Rock was a direct reaction to the overindulgence and overproduction of much of '70s mainstream rock, as well as to the overboard rock star posturing of uberbands like Led Zeppelin and the Rolling Stones. Pub Rock bands created their own concert circuit outside the scope of conventional venues, foregoing record contracts and concert hall performances for the sake of playing rootsy rock 'n' roll simply for the joy of it. Several veterans of the British Pub Rock circuit went on to form the core of important bands of the late '70s and early '80s, like Joe Strummer who helped start the Clash after leaving the 101ers, and Mark Knopfler who left Brewer's Droop for Dire Straits. Others went on to prominent solo careers, like Elvis Costello of Flip City, and Nick Lowe of Brinsley Schwarz.