David Bowie Is had a 75,000 private collection that Geoffrey Marsh was allowed to access for free.
Bowie had saved most of the artifacts, costumes, and props from his career and had almost 75,000 pieces in a private collection. Bowie allowed Victoria Broackes and Geoffrey Marsh, the V&A museum curators, free access to his archives for the show, although he did not get involved with how the pieces were displayed, nor the narrative of the show itself. 
