Here is a fascinating documentary from BBC Radio 4extra about the Zeppelin’s ‘Houses of the Holy’ album cover from the perspective of the boy who was photographed back then.
There’s a similar tale around the choice of the young girl on the cover of Blind Faith , She and her sister were approached by a photographer in a market somewhere and they chose the younger girl
Quite contentious at the time , probably a bit old hat these days but in 1969
“Picture Withheld for Decency”
If you’re talking about nude children in the service of art, I think that pendulum is swinging the other way; at least in Amerika.