An inquiry into allegations of sexual abuse at a leading private school for boys has revealed that more than 80 complaints have been made by former pupils against 32 members of staff covering a period spanning six decades.

An independent serious case review was set up almost three years ago to look into a proliferating number of abuse allegations at St Paul’s school in Barnes, south-west London, after five former members of staff were convicted of sexual offences.

The findings of the review, published on Monday, reveal for the first time the full scale of the allegations. In total, 59 former pupils or their families were interviewed as part of the inquiry and a number of new claims have been passed on to the police for investigation.

The majority of complaints date from the 1960s to the 1990s, but some of the staff implicated were working at the school up until 2017. While the review focused on St Paul’s, its 28 recommendations are intended to inform practice more broadly and address what it describes as gaps in the national safeguarding system.

“St Paul’s is unlikely to be different from many other institutions of its time,” the report states. “We should not judge response of the school in the past by today’s standards, but equally we should not forget that for some ex-pupils, the abuse that took place affected their school life and has continued to haunt them through adulthood.”

St Paul’s is one of the most high-profile independent schools in the country and has been attended by the likes of the former chancellor George Osborne, the fertility expert Robert Winston, the foreign correspondent John Simpson and the historian Dan Snow. Termly fees are £8,636 and boarding costs £12,997.

According to the 112-page review, at times sexual abuse appears to have been “known and tolerated by staff” at the school. The report includes details of allegations from the 1960s of boys being made to swim naked in the school pool and pupils having to remove their trousers for private caning.

The regime was described as “sadistic” and “brutal”, with physical violence when boys were struggling academically. Pupils were most at risk of sexual abuse from teachers who were friendly and seen as “cool” and who portrayed themselves as the “good guy”. One convicted abuser socialised with the rowing team in the pub; another invited boys for sherry in his study on Sundays.

The report describes grooming behaviours and “blurred boundaries” in the 1970s and 80s, with teachers buying alcohol for pupils and inviting them to their homes. One former pupil who was abused over an 18-month period said: “Once you have been groomed, when the individual strikes it is too late to get away either physically or emotionally.”

Ex-pupils told the inquiry there was a protective culture among staff and a fear that if you spoke out it would be held against you. One parent went further, saying that speaking out was impossible if you wanted to remain at the school.

The report details further physical violence in the 80s and 90s, including a teacher dragging a pupil around the classroom and throwing him out of the door and another dangling boys out of windows by their ankles.

Questions were also raised in the review about the rigorousness of recruitment practices at the school. One member of the PE team was found during the course of police investigations to have a previous conviction for gross indecency against a 15-year-old boy.

The report also details some of the consequences of the abuse. One pupil who was emotionally abused and humiliated between 2003 and 2005 experienced mental ill-health as an adult and killed himself while at university.

Since 2000 there have been four allegations of sexual abuse. Pupils and parents have become increasingly confident about speaking about abuse and the school has become increasingly aware of its responsibilities.

“We accept full responsibility for the past abuse experienced by pupils at the school and have previously apologised to survivors and our wider school community,” a spokesman for St Paul’s said.

“Today we repeat that apology unreservedly to those who have come forward and to those who have not felt able to. Our modern safeguarding regime is of a very high standard and we are determined to ensure, through continuous improvement of practice, that we never forget the lessons of our past.”

Chris Robson, the chair of the Richmond safeguarding children’s board, said: “I am grateful to the independent reviewers, professionals that worked with them and most importantly those who contributed, often giving very personal and difficult accounts. Through this process we have been able to understand what happened, why it happened and what it means for safeguarding practice going forward.”