And the bassist is comfortable with the resulting work being referred to as a "rock opera." Coma Ecliptic, released last week, tells the story of a patient in a coma who travels through his past lives. The band say: "He's offered a choice - stay, or move to the next in search of something more 'perfect.'"

Briggs tells Prog Sphere: "Tommy had talked about how he wished he didn't have to scream so much. On a given night he just wasn't feeling angry, or he was trying to get himself into that mindspace.

"His voice has come a long way since the early albums. That was an interesting catalyst to have in the back of our heads - focusing on the melody. It helps tell the stories."

He continues: "A rock opera is really not much different than a concept album," he says. "It's the telling of a story through music, and that's what we did.