However, he reveals that the cast did struggle a little when they all hit puberty.
“There was a period when we were the only boys and girls any of us knew,” Radcliffe explains. “So you know, we were all unbelievably horny from about the third film to probably about the end of the fifth.”
He adds, “Then it all settled down. But, God, for a few years…”
Harry Potter and the Half-Blood Prince opens in cinemas July 15.
Get daily celebrity updates on Twitter. @celebritytruth.