The instructor was conducting a revision exercise with the student/owner of the helicopter in preparation for a pending Licensing Standards Test (LST). During a downwind turn and flare Quick Stop manoeuvre, the main rotor blades struck the ground and the helicopter cart-wheeled for approximately 30 metres before coming to rest in an upright position. Both pilot’s evacuated the wreckage unaided with only minor bruising being sustained by the Instructor. There was no fire. The Report makes one safety recommendation.