6. Where, before the commencement, an agreement had been made to which subsection (3) of section 20 of the Act of 1964 applied, that agreement shall not be affected by the repeal of section 20 but shall have effect as if it referred to a right of compensation conferred by Article 23 (except in such a case as is mentioned in paragraphs (a) and (b) of section 20(2), the reference in paragraph (a) to Part I of that Act being read as a reference to this Order).