More than 250 people in the UK and Ireland have been convicted of child sexual abuse offences committed while they were Scout leaders or in other positions of responsibility within the Scout movement since the 1950s, according to analysis that raises questions about the organisation’s safeguarding procedures.

For decades, the Scout movement has been promoted as offering the chance to experience adventures and gain life skills but a review of offenders shows that for scores of children it has led to abuse at the hands of someone entrusted with their welfare.

The 255 cases include convictions for rape, indecent assault, voyeurism and the possession, creation and distribution of indecent/pornographic images.

The cases date back to the 1950s but also include contemporary examples such as Oliver Cooper from Bognor Regis, who was jailed for six years in October last year for three counts of sexual assault, against two six-year-old girls, taking indecent photographs of a child and 13 counts of voyeurism. The offences took place just over two years previously.

Also last year, Graham Avison from Audenshaw, Greater Manchester, was jailed for five years and seven months in November after pleading guilty to four counts of indecent assault between 1991 and 1995 against a boy whom he began grooming by giving him small gifts such as chocolate bars.

Abbie Hickson, associate in the abuse team at Bolt Burdon Kemp (BBK) solicitors, which compiled the interactive map of scouting abuse, said: “The Scout Association must do much more to protect the safety of its scouts from sexual predators going forward. At present there is an ongoing culture where there is potential for abuse to be inadvertently facilitated and not actively prevented.

“Much of their safeguarding policy relies on the integrity of the Scout leaders themselves, and is dependent on the individual choosing to adhere to it. It is important to remember that scoutmasters who perpetrate sexual abuse against scouts are by their very nature highly manipulative, secretive, devious and opportunistic individuals.

“There has to be a culture of transparency and trust and steps must be taken throughout all levels of the organisation so that sexual abuse within the scouts is actively prevented. When complaints are made, these must be investigated thoroughly and lesson learned, so that future abuse is prevented. Only then will the scouts of today and the future be protected from these sexual predators.”

BBK says the actual number of perpetrators and victims is likely to be even higher than detailed on its interactive map, which was based on public records, newspaper articles and independently verified documents, given that it only includes convictions. It does not include cases where victims did not report abuse or where prosecutors did not bring charges because of the difficulties of proving abuse where several years had passed or because the alleged abuser had died.

One example not included is that of Lucy Pincott, 27, details of whose case have been made public for the first time. She says she was sexually assaulted multiple times by a young leader when she was 13 years old.

The Crown Prosecution Service did not bring charges against her alleged abuser but Pincott, represented by BBK, agreed a £160,000 settlement with the Scout Association (the main UK scouting body) last year after an independent review was highly critical of its investigation into her complaint, although it did not admit liability.

Pincott said: “I want scouting to continue. It can be a great thing for many young people. However, they must be kept safe from those who would prey upon them.

“Many people will never recover from the damage of paedophiles and other sex offenders, especially when they are not believed and predators remain protected.”

A report on child sexual abuse in contemporary institutional contexts published on Tuesday by the independent inquiry into child sexual abuse in England and Wales based on analysis of files between 2017 and 2020 from the Disclosure and Barring Service, which helps employers vet potential employees, highlighted that alleged perpetrators included “scout or guide leaders who sexually abused children within those community groups”.

The Scout movement has also faced allegations of child sexual abuse in other countries. Earlier this, month, the Boy Scouts of America said it had reached an $850m (£620m) agreement with attorneys representing about 60,000 victims of child sexual abuse.

A Scout Association spokesperson said: “Nothing is more important than the safety of the young people in our care. In the UK, we have had over 10 million young members since our inception in 1907. We recognise that over that time there have been incidents of abuse. Any abuse of a young person is abhorrent, and we are deeply sorry for anyone who has suffered because of the actions of abusers.”

“Keeping young people safe from harm is something we take extremely seriously. We have robust safeguarding policies and procedures in place, which are publicly available, and we regularly invite external challenge and review. This has included a review by the NSPCC in 2012 and a further independent review by Hugh Davies QC in 2015. Recommendations from these reviews have been implemented.”