John Waddington, a founding guitarist of post-punk greats the Pop Group, has died, the band announced on social media. No cause of death was given. Waddington was 63 years old.

The Pop Group formed in the English city of Bristol in 1977, and released their landmark debut, Y, the same year. Led by Mark Stewart, the band mixed dadaist lyrics and anti-Thatcher agitprop with avant-garde compositions that expanded the prevailing punk sound. Frantic riffs combined with reggae legend Dennis Bovell’s production to channel dub and funk into a style that defined the postpunk era, as well as influencing early 2000s dance-punk revivalists like Liars.

In 1980, the Pop Group released the similarly adventurous—and more brazenly political—For How Much Longer Do We Tolerate Mass Murder? on Rough Trade, before disbanding, leaving Stewart to work with dub producer Adrian Sherwood on 1983’s Learning to Cope With Cowardice. Though Waddington did not join subsequent reunions, he played with Maximum Joy on their 1981 debut, Station MXJY, also produced by Sherwood, and contributed guitar to New Age Steppers and Judy Nylon records the same decade.

In its statement, the Pop Group called Waddington “an influential musician, and an integral member of the group.” The statement continued, “His energy and friendship will be sorely missed, and his unforgettable musicianship will always be remembered.”