Roger Waters was a primary creative force in Pink Floyd from 1965 to 1983. He first met Syd Barrett, who would become the band's lead singer and guitarist, during his school days when both attended a Saturday art class. He moved to London to study architecture at Regent Street Polytechnic and there formed a band with drummer Nick Mason and keyboardist Rick Wright; he played bass and sang. Barrett joined them, forming Pink Floyd. Though Barrett was the band's main songwriter at first, Waters wrote or co-wrote three songs on the first LP, The Piper at the Gates of Dawn (August 1967), including the solo composition "Take Up Thy Stethoscope and Walk." By the time of the group's second album, A Saucerful of Secrets (June 1968), Barrett had been replaced by David Gilmour and Waters had begun to take a more prominent role, contributing three songs and one co-composition to the LP. He also wrote or co-wrote all but one of the tunes for the band's soundtrack to the film More (July 1969), while his first solo work came on Ummagumma (November 1969), a two-LP set that consisted of one disc of live recordings and a second disc on which each bandmember contributed his own tracks. As of Atom Heart Mother (October 1970), Pink Floyd began to work up its material as a group, though Waters still contributed the sole composition "If." Working with Ron Geesin, he wrote the soundtrack for The Body (December 1970), his first work outside Pink Floyd. The band's next album, Meddle (November 1971), was entirely group written. But Waters wrote or co-wrote eight of the ten selections on Obscured by Clouds (June 1972), Pink Floyd's soundtrack for the film The Valley.