Karl Wallinger, the former Waterboys multi-instrumentalist who became the sole member of the successful ’80s and ’90s psych-pop project World Party has died. According to a statement from his publicist, Wallinger passed away yesterday. No cause of death has been reported. Wallinger was 66.

Karl Wallinger was born in the Welsh town of Prestatyn, and he was educated at British private schools. In the late ’70s, Wallinger formed a band called Quasimodo. Two of his bandmates later went on to form the Alarm, while Wallinger eventually became the musical director of the West End production of The Rocky Horror Show. In 1983, Wallinger joined the Waterboys, the maximalist rock band founded by Scottish musician Mike Scott. Wallinger didn’t play on the Waterboys’ self-titled 1983 debut, but he did play keyboards during their first performance, for the British live-music TV show The Old Grey Whistle Test.

Early on, the Waterboys were essentially a cult act, and Karl Wallinger’s ability to play tons of different instruments made him an invaluable contributor. By the time that the Waterboys released their third album, 1985’s This Is The Sea, Wallinger was helping to produce and arrange tracks, and he also co-wrote the single “Don’t Bang The Drum.” (“The Whole Of The Moon,” another single from that album, was a sleeper hit that reached #3 on the UK charts years later.) Karl Wallinger also helped the late Sinéad O’Connor record the demos that landed her a deal at Ensign Records, the Waterboys’ label, and they continued to work together for a few years. After the release of This Is The Sea, Wallinger left the Waterboys, and he signed the Ensign as a solo artist, taking on the World Party name.

In 1987, World Party released the debut album Private Revolution. Wallinger wrote and produced everything himself, and he played most of the instruments. Sinéad O’Connor sang on one song, and Karl Wallinger’s former Waterboys bandmates helped out on a few others, but it was essentially a one-man show. The songs showcased Wallinger’s love of ’60s psychedelia, with traces of ’80s funk-pop also making themselves known. The single “Ship Of Fools” was a minor hit around the world, including in the US, where it peaked at #27.

World Party’s 1990 sophomore album Goodbye Jumbo was a minor college rock sensation. The singles “Way Down Now” and “Put The Message In The Box” were hits on American alternative radio, with the former reaching #1. (It was just featured in our Alternative Number Ones column a few weeks ago.) World Party had another alt-rock hit with 1993’s “Is It Like Today?,” and they had songs on the Reality Bites and Clueless soundtracks, but the band slipped out of the zeitgeist, with one major exception.

The 1997 World Party album Egyptology was largely ignored, but the song “She’s The One” took off when British boy-band refugee Robbie Williams recorded a cover, releasing it as a single in 1999. Williams’ version became a massive success in the UK, going all the way to #1. Karl Wallinger didn’t give his blessing to the cover, and he was frustrated when someone else’s version took off, but it became a crucial financial lifeline for him. In 2001, Wallinger suffered a brain aneurysm that made it impossible for him to work.

World Party never recorded another album after 2000’s Dumbing Up, but Wallinger worked on projects like Big Blue Ball, a 2008 album with Peter Gabriel. World Party eventually got back to touring, too, and they played their last show in New York in 2015.

“Travel on well my old friend,” the Waterboys’ Mike Scott shared on Instagram. “You are one of the finest musicians I’ve ever known.”

UPDATE (3/22): Wallinger’s family has shared a message revealing his cause of death. “We can now share that Karl died suddenly from a stroke last week,” they write. “We have been overwhelmed by the love and support the World Party community has shown since then. Thank you all so much.
With love, Suzie, Louis & Nancy”

Below, check out some of Karl Wallinger’s work.