Shirley began playing drums for the band Apostolic Intervention at an early age and was later recruited by Steve Marriott to join the then newly formed rock band Humble Pie, when he was seventeen years old. Shirley remained as Humble Pie's drummer throughout the group's entire history. He also worked on Steve Marriott's solo projects, such as Pack of three and was a co-founder of the popular 1980s group Fastway. Shirley co-wrote Fastway's biggest hit, "Say What You Will".
Shirley returned to the UK in 1999. In 2000 he reformed Humble Pie with their original bassist Greg Ridley and another former band member, guitarist and vocalist Bobby Tench. They recorded Humble Pie's eleventh studio album Back on Track (2002) and he also appeared in a memorial concert for former Humble Pie bandmate Steve Marriott. More recently he has performed with the Deborah Bonham Band.