20.—(1) Where on any appeal the Court substitutes a conviction of a different offence or substitutes a different sentence, that conviction or sentence shall, for the purposes of the Defence Acts, 1954 to 1979, and any instrument made thereunder, be deemed to be a duly confirmed finding or sentence of a court-martial.

(2) Notwithstanding section 206 of the Act of 1954, the Court may by order provide for the date on which a sentence substituted by it, or passed by a court-martial and not varied by the Court, shall commence or take effect.