A person is guilty of an offence against this Act who, without lawful authority or excuse, proof of which shall lie on him—
(a)refuses to an inspector or other officer, acting in execution of this Act, or of an order of the Minister, or of a regulation of a local authority, admission to any land, building, place, pen, vessel, boat, aircraft or vehicle of any other description which the inspector or officer is entitled to enter or examine ; or
(b)obstructs or impedes him in so entering or examining; or
(c)otherwise in any respect obstructs or impedes an inspector or constable or other officer in the execution of his duty, or assists in any such obstructing or impeding.