Conduct by a person (A) which would otherwise be an offence under any of Articles 51 to 54 against another person (B) is not an offence under that Article if, immediately before A became involved in B's care in a way that falls within Article 55, a sexual relationship existed between A and B.

Paragraph (1) does not apply if at that time sexual intercourse between A and B would have been unlawful.

In proceedings for an offence under any of Articles 51 to 54 it is for the defendant to prove that such a relationship existed at that time.