Glen Turner left the band at that point, and an advertisement for a guitarist resulted in the addition of both David Alan "Ted" Turner and Andy Powell, who provided the basis for the sound of the new lineup with intertwining riffs and phrases drawn from both soul and blues, coupled with Martin Turner's melodic bass sound and Upton's jazz-influenced drumming. A new name was called for, and after several suggestions by Copeland that proved unacceptable, "Wishbone Ash" was chosen from two lists of words. The group rehearsed for weeks at Copeland's home, working out an entirely new repertoire, and played their first gig opening for the Aynsley Dunbar Retaliation. It wasn't too long before they were opening for Deep Purple, where a sound check jam between Powell and Ritchie Blackmore led to a recording contract with the American Decca label.

Their self-titled first album appeared in 1970; Pilgrimage and Argus followed over the next two years, and each showed a major advance in the band's sound. The release of 1973's Wishbone Four reflected a greater maturity to the group, and was their first fully developed album, with songwriting that didn't hide behind a progressive pose but luxuriated in the members' folk music inclinations, without compromising the harder edge of their music. The album also saw the departure of Ted Turner, who was replaced by Laurie Wisefield.

Locked In and New England followed; Martin Turner departed after 1979's Just Testing, to be replaced by ex-King Crimson bassist/singer John Wetton. Wishbone Ash soldiered on through the 1980s, and in 1986 even got back with Copeland, by now a major player in the recording industry by virtue of his management of the Police and his founding of I.R.S. Records. Wishbone Ash's history came full circle with the reunion of Powell, Upton, Ted Turner, and Martin Turner, and the recording of three albums for I.R.S.. They remained a working band into the 1990s, led by Andy Powell and Ted Turner and touring and recording regularly.