Agnew began playing in bands at about the age of 11. His first band was called the Attack, where he played drums and wrote all their lyrics and music. He started Almost 21 in his first year of high school with Jay McCarty on vocals, himself on guitar and vocals, Hal Hughes on guitar, Tom Hughes on bass guitar, and John Knight on drums. Almost 21 released a demo as a 7" vinyl on Gummopunx. "
Ancient Artifacts", "
Horse Bites Dog Cries",
Team Goon, and "Live at a Dive" were released while Agnew was in the band. Around 1986, the Adolescents began working on a return with the original line-up, but Frank Agnew left the project and Alfie Agnew replaced him. He played with the band for several months, recording guitars and backing vocals on the second Adolescents album,
Brats in Battalions, before leaving to attend to university work. and their first live appearance in August of that year. They released a live album,
Live at the 100 Club, in January 2019. Their fourth studio album,
Séance, was released in November 2020. ==Personal life==