A woman labelled a "predatory paedophile" by police has been given an indeterminate prison sentence after she admitted sexually abusing children.
Carol Clarke, 46, assaulted children she followed into toilets in Grimsby and other places in Lincolnshire.
Grimsby Crown Court heard that Clarke, of Cromwell Road, Grimsby, had admitted abusing children, aged between four and seven, over 30 years.
Judge David Tremberg said she would serve a minimum of four years in jail.
He told Clarke she would only be released from prison once parole board members were satisfied she no longer posed a risk to young children or the public.
"This is a sad and deeply troubling case," he said.
Det Sgt Stewart Watson of Humberside Police said: "Predatory paedophiles such as Carol Clarke are rare.
"Experts agree that women commit only a fraction of child sexual abuse but, as little is known about female offenders, it is difficult to be accurate.
"There are still those members of the general public and even some experts who ignore women's capacity for sexual abuse.
Judge Tremberg told her: "From the time you were a very young woman you have had and maintained a very worrying sexual preference, in particular young girls ."
Dozens of offences
Clarke, who won a place at Cambridge University after being head girl at her school, was "clearly an intelligent woman" and could have endeavoured not to indulge her interest in children, he added.
At an earlier hearing Clarke admitted abusing young boys and girls, with some of her offences dating back to before 1992.
Her offences ranged from assaulting children in toilets in Grimsby town centre to targeting them at a caravan park in Woodhall Spa, Lincolnshire.
Gordon Stables, prosecuting, said the case had been brought based on the confessions of Clarke, after she was reported to police earlier this year by a mental health care worker.
She is believed to have committed dozens of offences.
Mr Stables told the court Clarke had taken a job in an ice-cream van in order to try to get close to children, and had used events organised by her church to come into contact with youngsters.