The Queen actress confessed that although she does not mind looking after youngsters every once in a while, she is always pleased when they are collected by their mother and father.
She told the Sunday Times Magazine: "I've never been hugely maternal, but I've always loved children as an aunt, a naughty aunt. I'm very happy to be able to give children back to their parents... Not that I've actually ever been alone with them."
The star, 63, believes her desire to steer clear of motherhood stems from a traumatic video of a woman in labour she was shown at school when she was 13.
She added: "It was horrific and it gave me an absolute horror of childbirth.
"They herded us all together into a room with other girls the same age, and boys. The lights came up at the end and every kid was white and sick and silent. The boys couldn't look at the girls and the girls couldn't look at the boys."