Funny enough I'm sat in a 4 day health and safety course and we've just been talking about regulatory responsibilitiea, duty of care, risk assessments and all that fun stuff :-( The tutor was very impressed by this situation. At a minimum it must be reported to the Health & Safety Executive who'll investigate. It's very likely the "instructor" will face charges under the Health & Safety at Work Act. It can end up in court and while he could face prison it would most likely be a fine. Unfortunately its unlikely to stop the guy from working in thie area but at least a successful prosecution makes a civil claim by the casualty more likely to be successful. Maybe the claim could be big enough to put the guy out of business.