Teenage paedophile Opemipo Jaji, 18, has been sentenced to at least eight years at the Old Bailey for raping an 11-year-old girl in a north London park.
The 18-year-old, from Edmonton, north London, had just left his probation officer when he spotted the child going home from school on a bus before following her and dragging her into a park to subject her to a three-hour rape ordeal.
Mr Justice Singh at the Old Bailey told Jaji that he had given careful consideration to whether he could impose a lesser sentence than life, for example a determinate sentence combined with an extended term.
"However, in all the circumstances of this case, I do not believe that the public would be adequately protected from you if you were the subject of any sentence other than a life sentence," he said.
The judge told Jaji that the eight-year minimum was not the actual term he would serve, but the minimum before he could be considered for release by the Parole Board.
"The Parole Board will only direct your release on licence if it is satisfied that you are no longer a danger to members of the public."
Jaji had been given an 18-month supervision order six months before for making indecent images of children.
A year earlier, he had sexually assaulted and robbed a 12-year-old schoolgirl on a housing estate.
Later, he was given a 10-month detention and training order which he went on to breach.
He was found guilty of rape following a trial at the Old Bailey in April.
He had denied raping the girl in Jubilee Park, Enfield, north London, in November, last year.
The child gave evidence against him on videolink during the trial.