Difficult to see what roller derby could have done though about this. There are people suggesting DBS checks should have been made but if this is her first offence she wouldn't have been flagged by the system anyway.
This is what they say on Facebook:
"As stated we’re looking in to how we can improve and better safeguard people around us. Unfortunately we do not work directly with children or vulnerable adults which doesn’t validate doing a DBS check for our members. In this situation, the person left our membership more than a year ago and a DBS check on our coaches/members still would not have brought this up, as stated earlier. It’s hard to say what our stance is going forward due to the information being released 48 hours ago. We have a lot to discuss, plan and then put in to practice."