17.—(1) In any proceedings for an offence under these Regulations it shall, subject to paragraph (5), be a defence for the person accused to prove that he took all reasonable precautions and exercised all due diligence to avoid the commission of the offence by himself or by a person under his control.
(2) Without prejudice to the generality of paragraph (1), a person accused of an offence under regulation 4 or 13(1)(a) who did not —
(a)prepare the material or article in respect of which the offence is alleged to have been committed; nor
(b)import it into the United Kingdom,
shall be taken to have established the defence provided by paragraph (1) if he satisfies the requirements of paragraphs (3) and (4).
(3) A person satisfies the requirements of this paragraph if he proves —
(a)that the commission of the offence was due to an act or default of some other person who was not under his control, or to reliance on information supplied by such a person;
(b)that either —
(i)he carried out all such checks of the material or article in question as were reasonable in all the circumstances, or
(ii)it was reasonable in all the circumstances for him to rely on checks carried out by the person who supplied him with that material or article; and
(c)that he did not know and had no reason to suspect at the time the offence was committed that his act or omission would amount to an offence under these Regulations.
(4) A person satisfies the requirements of this paragraph if the offence is one of sale and he proves —
(a)that the commission of the offence was due to the act or default of some other person who was not under his control, or to reliance on information supplied by such a person;
(b)that the sale of which the offence consisted was not a sale under his name or mark; and
(c)that he did not know and could not reasonably be expected to know at the time the offence was committed that his act or omission would amount to an offence under these Regulations.
(5) If in any case the defence provided by this regulation involves the allegation that the commission of the offence was due to an act or default of another person, or to reliance on information supplied by another person, the person accused shall not, without leave of the court, be entitled to rely on that defence unless —
(a)at least seven clear days before the hearing; and
(b)where he has previously appeared before a court in connection with the alleged offence, before the expiration of one month from his first such appearance,
he has served on the prosecution a notice in writing giving such information identifying or assisting in the identification of that other person as was then in his possession.