Famous in the early 1970s for such hit songs as "Get Down" and "Alone Again (Naturally)," this Irish vocalist released several top United Kingdom albums, including Back to Front and I'm a Writer, Not a Fighter.
While studying at the Swindon College of Art, he became the drummer for Rick Davies' early music group, Rick's Blues. His first Top Ten hit was the 1970 track "Nothing Rhymed."
In 2011, he released an album titled Gilbertville.
Born Raymond Edward O'Sullivan, he grew up in Waterford, Ireland and Wiltshire, England. He and his Norwegian wife, Aase, welcomed their first daughter, Helen-Marie, in 1980, and their second child, Tara, in 1982.
In the late 1960s, music manager Gordon Mills (who also represented the popular singer Engelbert Humperdinck) signed O'Sullivan to his MAM Records label.