Richard Holmes is free to pursue his hagiolatry of Gaspard-Felix Tournachon aka Nadar however he wants but I think he misunderstands this great man's accomplishments.
Unlike most people in APUG Felix Nadar, for the grand bulk of his career, did no camera work, no darkroom work, and produced no photographs by his own hand. His studio employed "operators" to do framing, focus, and exposures at the camera, a team of assistants running from and to the darkroom with wet plates, and "printers" on the roof of the building contacting out albumen paper. Felix Nadar was a photographic impresario whose precious talent was self promotion and the capacity to attact and schmoose famous sitters to his studio. Without him many iconic images of the European glitterati of the late nineteenth century would not decorate history.