66. It is a defence for a person charged with an offence under regulation 65 to prove that—
(a)he or she was not reasonably able to comply with the provision in question by reason of an emergency or grave danger and that he or she took all steps as were reasonably practicable in the circumstances for—
(i)minimising any threat to the public or the environment; and
(ii)ensuring that the provision in question was complied with as soon as reasonably practicable after the event; or
(b)if there is no emergency or grave danger, he or she took all reasonable precautions and exercised all due diligence to avoid the commission of the offence.