Billboard sat down with co-directors MacMahon and McGourty to learn how they locked in interviews with Page, Robert Plant and John Paul Jones, why the film stops after Led Zeppelin II and how some of the band’s contemporaries reacted to screenings of the movie.

DECIDER spoke to director-writer Bernard MacMahon and producer-writer Allison McGourty about this project that was decades in the making.

The release of the Becoming Led Zeppelin documentary pushes several albums by the band, including Led Zeppelin, Led Zeppelin II, and Four Symbols, up the UK charts.

In retrospect, it makes sense that backing Bassey would prove formative: So much of Led Zeppelin was about power, poise and drama (or melodrama, if you think of the first album's overwrought "Babe I'm Going to Leave You").