Music essayist Film Retrospective has taken a rare look inside the 1968 recording of ‘Led Zeppelin I’ at Olympic Studios, and the detail that stands out most is just how prepared the band was from the moment they walked in the door. Engineer Glyn Johns, accustomed to working with the Rolling Stones and their famously relaxed approach to punctuality, was caught off guard by a band that showed up, set up, and started playing within minutes of arriving. Jimmy Page had it all mapped out before a single tape rolled: “I knew exactly what I wanted to do in every respect. I knew what all the guitars were going to do and how it was going to sound, everything.”