31.—(1) Conduct by a person (A) which would otherwise be an offence under any of Articles 23 to 26 against another person (B) is not an offence under that Article if, immediately before the position of trust arose, a sexual relationship existed between A and B.
(2) Paragraph (1) does not apply if at that time sexual intercourse between A and B would have been unlawful.
(3) In proceedings for an offence under any of Articles 23 to 26 it is for the defendant to prove that such a relationship existed at that time.