There is a common law basis for this and that is the law of tort. Any person who acts, or fails to act, as a result of which s person is injured or killed can be found liable for their act or omission. In this situation it would be the failure to report and therefore an omission. Note also that if a person is killed there is statutory liability under the corporate mansaluaghter legislation. I hope that helps. Please leave a positive rating so that I am credited for my time.
Yes, most definitely. The test would be whether an ordinarily competent contractor would have been able to assess the risk.
Yes, I'm aware of that case. The distinction is that in your case there is a specifically published instruction to contractors to intimate any infringement and the notice makes it clear that to do nothing is not an option.