In 2007, the three surviving members of Led Zeppelin reunited at London's O2 Arena for their first full-length concert in nearly 30 years. But it wasn't until 2012 that the band released CD and DVD versions of the show as Celebration Day. A new interview with Jimmy Page's former managers, Peter Mensch and Cliff Burnstein of Q Prime, explains the reason for the five-year delay.

Speaking to Billboard, Mensch, who had previously managed Page separately, reveals that it was because Led Zeppelin "were fighting internally." "Jimmy called me up and asked me to come back to solve the problems," Mensch explained. "It had been five years since I was last on the case. He needed someone to mix the record."

It was Mensch's idea to hire Alan Moulder -- known for his work with Smashing Pumpkins, Nine Inch Nails and the Killers -- to work on the audio. Mensch then had an experience he said he'll never forget. "I’m watching them mix 'Kashmir,' and I'm watching Jimmy Page miming 'Kashmir' as Moulder is putting the final touches on it," he recalled. "And that for me was like, 'F--- me.'”

Mensch eventually pulled the plug on his working relationship with the guitarist -- their earlier deal ended when Page fired Q Prime -- but the firm stayed with him long enough to get Led Zeppelin's recent reissue campaign off the ground. "[T]hose box sets were mostly [Cliff’s] and my idea," Mensch noted. "And they're structured the way I wanted them structured."

Still, Burnstein added that "We're very proud of what we contributed as Jimmy's management to the Led Zeppelin legacy."

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