The supermodel shared the snap with the anti-censorship hashtag #FreeTheNipple on the evening of 15 September.
At the time HuffPost UK Style reported that the following morning Instagram hadn't taken the photo down, despite their reputation for censoring photos in which female nipples are exposed.
However, two days later that seems to have changed. The photo is no longer on Campbell's Instagram page.
HuffPost UK Style contacted Instagram to find out if Campbell's picture had been taken down for breeching their community guidelines, but they declined to comment on the individual case, simply stating:
"Images are removed from Instagram for one of two reasons:
"1) The Instagram community member chooses to take the image down.
"2) We remove images reported to us by the Instagram community which breach our guidelines."
However Naomi's nipples are still free on her Twitter account:
