This Act shall apply in relation to any authority for the detention or guardianship of a person who was liable to be detained or subject to guardianship under the M1Mental Health (Scotland) Act 1960 immediately before 30th September 1984 as if the provisions of this Act which derive from provisions amended by section 5 of the M2Mental Health (Amendment) (Scotland) Act 1983 and any amendments in Schedule 2 to that Act which are consequential on those sections were included in this Act in the form which the provisions from which they derive would take if those amendments were disregarded; but this provision shall not apply to any renewal of that authority on or after that date.