Carefully monitor the contractor’s activities when they are on the premises. We must exercise due diligence and actively enquire into what the contractor is doing - it is not acceptable just to leave them to it.
If you think the contractor may be working unsafely – stop the work and seek advice.
Be decisive about this. For example if the work involves working at height and you think the contractor is operating unsafely by not taking sufficient precautions (such as using scaffolding which is tagged "safe" and in date), then consider stopping the work straight away if the risk of injury is high. If the risk is low, consider taking advice before making your decision.