More than 3,000 of you wrote in demanding action after we revealed how "mentally ill" children in bleak, State-run homes are kept locked up for up to 23 hours a day.

Younger children are kept in "cages" 4ft high. Older youngsters live in 8ft by 3ft cells with bars up to the ceiling.

Ms Rowling, who is pregnant with her third child, said last night: "I am delighted that Sunday Mirror readers have spoken out in such numbers against the use of cage beds.

"I hope this takes us a step nearer the abolition of this dreadful practice."