In a BBC television programme to be shown next week, Irons suggests that society - while protecting children - should not become so rigidly obsessed with paedophilia that it prevents adults demonstrating affection to children.
“It’s very difficult because children under 16 are immensely attractive, any father will tell you,” Irons said. “We have to accept that, understand it for what it is and not become hysterical about it.”
Irons starred in the film Lolita, in which a married college lecturer falls for an underage girl.
“It’s very shocking stuff that he is saying,” said Eileen Prendeville, a child sex abuse therapist.
“There has to be hysteria in relation to paedophilia, but it’s a consequence of the fact that paedophiles exist and that they continue to abuse children,” she said.
Ms Prendeville is former national clinical director of Children At Risk in Ireland Foundation.
“One of the difficulties of what he is saying is that it legitimises a sexual interaction between parent and child, on the basis that some people could say it’s initiated by the child,” she said.
The actor made the remarks when asked what it was like playing Humbert Humbert, the college lecturer who falls for an underage girl in Lolita.
Interviewed by Jeremy Vine for a programme to be broadcast on BBC1, Irons said: “Strangely enough, Humbert Humbert is not a paedophile ... because he knew he was doing wrong. That’s his tragedy in a way.”
Irons described the difficulties of judging the line between natural affection and paedophilia with reference to his family.
“I remember when my son was 12 he was like a god,” he said. “He just went through that sort of golden time for about 18 months. Parental love is sexual. Boys will flirt outrageously with their mothers.”
Irons’s remarks were deemed “very odd” by Esther Rantzen, chairwoman of Childline, the British charity for abused youngsters.
“Immensely attractive is not the best thing to say about children under 16,” said Ms Rantzen. “Appealing or charming are more appropriate.”
The dilemma voiced by the actor, who shot to fame in the ITV drama Brideshead Revisited before films such as The French Lieutenant’s Woman and Damage, arises from more than his experience of appearing in films addressing controversial topics.
The actor, who owns the 15th-century Kilcoe Castle near Ballydehob in West Cork, illustrated his point by describing what happened when he presented prizes at a fete near where he lives in the Oxfordshire countryside.
“I had done my little speech and a girl from the local school wanted to show me around the art exhibits.
“I was very happy to go. I had my arm on the shoulder of the girl as we walked around. But the teacher was there and looked at me and said: ‘Don’t do that.’ I said: ‘What?’ He whispered to me. I then said: ‘I’m sorry.’
“But I suddenly felt like a criminal. And I thought ‘What are we doing to this new generation? We can’t smack them or hug them. What strange people are we going to bring up’?”
The need to protect children, he said, should be balanced against demonstrative instincts. “We’re animals. We should hug our young. We should hold our young. We shouldn’t suddenly, when our daughter becomes 12, stop her sitting on our lap, stop hugging her. What’s she going to think about affection, about human nature if that happens in her upbringing?”