There is an idea that people should never be shocked - but no healthy person lives a day without being offended. It is not very healthy

John Mortimer

Artist and critic Edward Lucie-Smith says the heightening of concern over paedophilia and simultaneous increase of depictions of adult nudity has changed what is taboo.

Benetton's newborn baby was one of the most-complained about adverts ever

"In the 19th century, the depiction of pre-pubescent children was generally regarded as a depiction of innocence with no suggestion that there was a sexual element.

"In the days of hippies and flower power there were lots of pictures of hippy fathers dangling naked children on their knee - nobody thought anything of it.

"One could say that the structure of taboos is in the process of being inverted."

Author John Mortimer has seen society's sense of taboos shift since he was a junior counsel in the infamous Oz trial of 1971 where the conviction, overturned on appeal, of those behind the counterculture magazine became a cause celebre.

John Mortimer: We live in a dreary puritan country

He told BBC News Online that even in the absence of high-profile obscenity trials, political correctness had led to a puritan Britain with as many taboos as ever.

Renaissance paintings

"We are living in a dreary puritan country - we are marching relatively backwards."

"Naked children, running around or flying, have been in every Renaissance painting."

In some ways the public have been more tolerant out of a sense of frustration that nothing can be done

John Beyer Mediawatch

Mr Mortimer said our sense of what is taboo and what is decent was not determined reasonably but tailored for a minority.

"It is part of this great desire for control of people's lives.

"Censorship has been good for artists because it puts them on their mettle to defy it.

Codes of conduct

"There is an idea that people should never be shocked - but no healthy person lives a day without being offended. It is not very healthy."

This naked girl fleeing a napalm attack in Vietnam often appears in papers

Professor Graham Clarke, a specialist in photographic art at Kent University, says a taboo "can be as much to do with a nude photograph or somebody who has no legs, anything that disturbs or questions is taboo - taboo really becomes the things you don't want to see".

Mr Lucie-Smith agrees there is an ebb and flow of taboo in UK society.

Growth of psychoanalysis

"The line swings back and forth - some things become more permissible, some things less and it isn't a linear progression.

"Our ideas about the intention of pictures of naked children have been influenced and one might say corrupted by the growth of psychoanalysis and its emphasis on child sexuality, by a loss of innocence."

He points to the numerous examples of nudity in religious art through the ages.

Tierney Gearon's photos have caused a storm

But it is not only art that flirts with taboos with Sophie Dahl's nude pose for Opium perfume and a London Underground poster featuring a seven-year-old Martin Amis smoking both banned.

Public anxiety

John Beyer, director of Mediawatch, formerly the National Viewers and Listeners Association, insists people have a right to be protected and to protect children.

"There is a great deal of public anxiety about exploitation of children and the sexual abuse of children."

He says the lack of enforcement of obscenity laws has led to other taboos being dropped out of a sense of powerlessness, adding: "In some ways the public have been more tolerant out of a sense of frustration that nothing can be done."

Prof Clarke points to Benetton's famous newborn baby poster campaign of 1991, one of the most complained about in the history of advertising, with 800 people finding it offensive.

"It was one of the most natural things one could see - a newborn baby which hasn't been washed, a completely innocent, celebratory image and yet people objected.

"In general, it is a matter of whether the child is being exploited ... if the obvious intention is to use the body rather than reflect the child, its sense of joy, happiness or sadness ... when the body becomes treated as an object."