The brutal attack on an 11-year-old and a nine-year-old was by two brothers, aged 10 and 11, in Edlington, South Yorkshire, in 2009.
The brothers lured their victims to a secluded spot and subjected them to 90 minutes of violence and sexual humiliation.
The victims, who are uncle and nephew, were strangled, hit with bricks, made to eat nettles, stripped and forced to sexually abuse each other.
The attackers were locked up in 2010 for a minimum of five years.
A serious case review concluded the attack was "a preventable incident" and identified "more than 30 opportunities that could, with different and clearer judgment and action have reduced the harm suffered by (the brothers) and their harm to others."
Weaknesses remain in child protection services at a council which was heavily criticised after two boys tortured and sexually humiliated two other youngsters, according to a new report by Lord Carlile.