BILL HENSON, the celebrated artist whose photograph of a nude child in 2008 was slammed as ''revolting'' by the then prime minister Kevin Rudd, last night said it was ''sheer nonsense'' for critics to argue that a child did not have the capacity to consent to modelling nude.

''People do get confused with notions of consent and harm,'' Henson told a standing-room-only audience of 700 at Melbourne's Federation Square.,

''But as my barrister friends remind me, kids do consent to all kinds of significant things all the time. Parents consent to babies' injections, a 10-year-old consents to dental appointments, a 15-year-old can consent to a sex change in this state. Consent is something that increases gradually as a child moves towards its majority.

''Every day children consent to activities that result in real harm,'' he said, saying a 12-year-old child going out to play football could ''find himself in a wheelchair for the rest of his life. There is harm done to children by parents consenting to activities every day''.

Henson's speech, launching the 2010 Melbourne Art Fair, has been eagerly awaited because he has only spoken rarely since he sparked a national debate about art and pornography and the rights of children in May 2008.