His top pick was Electric Ladyland by The Jimi Hendrix Experience. Halford says: "Listening to this music at the time it was being made is something I'll never forget.

"Simply because of the sheer audacity of this extraordinary guitar player and artist. He made the room light up so vividly. To listen to the sounds that he made with the electric guitar was unbelievably special.

"Things were changing at this time. The music in general was getting louder. Marshall amps were being made, speaker cabinets were being used - everything was getting bigger, louder, more impactful. I think Jimi had something to do with that."

He also praises Led Zeppelin II, describing it as the "roots of heavy metal." Halford adds: "When I heard the riffs that Jimmy was doing, I got a real sense of where things were going. Even though Led Zeppelin never expressed, 'We've got some heavy metal in us,' it's quite apparent that it was there all along."