We counted a total of 281 in the main, free galleries on the day we went: 89 belonged to women, 111 to men and 81 to children. But it's clear that unless they're on Christ (or other men for that matter), their exposure is time period-dependent. As a general rule, women's nipples were rather more visible during the Renaissance; one of the National's more risqué images, Bronzino's Venus and Cupid, featuring a nipple being tweaked, would have been covered during more puritanical eras, we were told.
Today, we're still far from comfortable with the female nipple. They're seen as sexual, titillating and generally uncouth. They should be hidden from view lest people be corrupted - even during the perfectly natural act of breastfeeding.
And if ladies aren't willing to cover up, whether it be in the digital realms or in real life? Well then, prepare to get blocked online, arrested on the streets or asked to leave establishments, as was the case across many of the countries and cultures Index explored. The V&A recently made headlines when a woman was asked to cover up when breastfeeding; she has since received an official apology.
But women are fighting back. While Free the Nipple, a gender equality campaign that seeks to highlight oppressive double standards, is the best known organisation, with their famous faces and catchy hashtag, there's a growing list of others campaigning for nipple equality.
Nadine Gary from GoTopless highlighted that yes the female nipple can be sensual, but so can other parts of the anatomy that go freely on display. We need to stop singling them out.
GoTopless have declared 2017 the year of equal topless rights, in part in anticipation of a case at the US Supreme Court later this year. The case centres on Sonoko Tagami, who is suing the city of Chicago after being fined for exposing her nipples during an event to promote women's rights to bare their breasts in public.
Other initiatives that highlight the absurdity are the Genderless Nipples account on Instagram, which invites viewers to guess whether the zoomed in nipple belongs to a man or a woman (now there's a challenge), and online tool the Internet Acceptable Male Nipple Template, a cut-out of a male nipple that women can paste over their own. This was set up by artist and academic Micol Hebron after Instagram censored an image of herself appearing topless at a breast cancer fundraiser art exhibition. Yes, you read correctly.
Europa has received a backlash. Twitter is full of comments and pics like one of Homer Simpson looking at his exposed flat chest - legal! - and Homer with bare breasts - illegal! Perhaps people are finally waking up to the fact that when it comes to nipples, the lines really shouldn't be blurred, whether they're male or female.
• Jemimah Steinfeld is deputy editor of Index on Censorship magazine. A history of nipples and an investigation into current initiatives is published in the next issue, out shortly.
