“The lack of compulsory sex and relationship education in academies and free schools is storing up problems for later on in life, creating a ticking sexual health time bomb, as we are seeing in those who have recently left school.” She added that there was a “shockingly high” number of sexually transmitted infections (STIs) diagnosed in teenagers and young people. Official figures show there were 78,066 new STI diagnoses among 15 to 19-year-olds in England in 2015, the LGA claimed, and 141,060 among 20 to 24-year-olds. “The evidence suggests that when designed and delivered in the right way, SRE can have a really positive impact on a pupil’s development,” Ms Seccombe said. “However, we are also conscious that some parents may wish to remove their children from this, which is why we are saying there should also be provision for parents to opt their children out of lessons, if they consider this to be in the best interests of their child.” A Department for Education spokesman said: “High-quality education on sex and relationships is a vital part of preparing young people for success in adult life. “It is compulsory in all maintained secondary schools and, as the Education Secretary said recently, we are looking at options to ensure all children have access to high-quality teaching in these subjects. “We will update the House during the passage of the Children and Social Work Bill.”