3In any such proceedings as are mentioned in sub-paragraph (1) of the foregoing paragraph a certificate purporting to be signed by an authorised analyst and certifying the presence of any substance in any such sample of heavy oils as may be specified in the certificate shall be evidence, and in Scotland sufficient evidence, of the facts therein stated:
Provided that (without prejudice to the admissibility of the evidence of the analyst, which shall be sufficient in Scotland as well as in England) such a certificate shall not be admissible as evidence—
(a)unless a copy thereof has, not less than seven days before the hearing, been served on the person charged with the offence; or
(b)if that person, not less man three days before the hearing or within such further time as the court may in special circumstances allow, serves notice on the prosecutor requiring the attendance at the hearing of the person by whom the analysis was made.