The guidance is that all Forest School leaders should retain records of participants for at least 6 years, whether a participant attended for one session or on numerous occasions. This is due to the fact that the legal system allows a potential claimant to make a claim 3 years after the date of discovery of an injury (whether it is a valid claim or not).
In the event of a claim insurers need all the participant’s details, records, risk assessments, etc in order to help defend you. The other aspect to also consider is that the HMRC require you to hold all financial accounts for 6 to7 years.