Back in the prehistoric '70s, "jam band" was not yet an operative term. Outfits loosely grouped as "progressive" featured extended instrumentals, expanded melodies, and highly orchestrated arrangements. Most bands of this persuasion were fronted by multiple keyboards -- as well as guitar.
Formed in 1969, Brit quartet Wishbone Ash managed much of the same acrobatics with the classic two guitars, bass, and drums configuration. Like the quintessential proto-jammers the Allman Brothers, Wishbone Ash locked onto a twin-lead-guitar signature. The tandem of Andy Powell and Ted Turner highlighted well-received early '70s releases like Pilgrimage and Argus, expanding the band's palette by occasionally going acoustic. Powell additionally distinguished himself by brandishing a Gibson Flying V, rivaling blues master Albert King for association with the distinctively styled axe.
The band has survived for three and a half decades, reconstituting itself periodically. Powell has been the constant, with such successive members as bassists John Wetton (King Crimson, Roxy Music) and onetime Spider From Mars, Trevor Bolder. The current lineup, most of which has been intact for all of this century, consists of Powell, bassist Bob Skeat, drummer Ray Weston, and guitarist Muddy Manninen. The band's catalog now approaches 40 albums, including forthcoming live and studio discs.