The late John Bonham was known for many things - most notably as one of history's best drummers and one-fourth of British rock band Led Zeppelin - but speaking in public was not one of them.
This means making a documentary about the band - who broke up following Bonham's death in 1980 - is quite hard, as there are little in the way of recordings of past interviews.
That is why when director and producer Bernard MacMahon found a bootleg copy of an interview with Bonham on vinyl, he knew he had to find the original copy for the band's first authorised documentary, Becoming Led Zeppelin, which premiered at Venice Film Festival last week.
The search led him to the National Film and Sound Archive, after he recognised the interviewer's accent as Australian. It was there, that only a week prior, curators had found the interview in a stack of 8000 tapes donated by Sydney radio station 2SM.
"We received a really large collection from radio station 2SM to us in some years ... and audio tapes from radio stations tend to have information scrawled on the box, but now much beyond that - no listings or catalogues or anything like that," archive curator Thorsten Kaeding said.
"What we need to do to figure out what's on them is basically listen to them and go through them and then catalogue them.
"These audiotapes or interviews are designed for radio, but they're often wide-ranging and a lot longer than what went to air.
"That's why this one was so exciting for the documentary makers because they had the other three members of Led Zeppelin who was still alive interviewed for it - so they were able to give their story - but John Bonham because he passed away in 1980 wasn't able to."
The interview is from early 1972. The band was one of the biggest rock bands in the world, having just released its fourth studio album, Led Zeppelin IV - which featured the rock anthem Stairway to Heaven.
It was ahead of their Australian tour that Australian broadcaster Graeme Berry scored himself an interview in Led Zeppelin singer Robert Plant's home, interviewing both Plant and Bonham for 2SM.
The result was one hour of audio that revealed a side of Bonham that was rarely seen - if at all - during interviews.
"John Bonham is open and engaged and friendly in the audio. And that's unusual for interviews with John Bonham," Mr Kaeding said.
"For most of his career, he was not all that friendly with journalists and very rarely opened up in this sort of way. So it's a really important historic document, in that sense for John Bonham and his career.
"Bonham also talks a little bit about his life before being a drummer for Led Zeppelin, about forming Led Zeppelin and the first gig they ever played and all of that sort of thing. It was done, really at the height of their popularity."
Becoming Led Zeppelin is yet to be given an Australian release date.
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