(1) The date of making of every statutory instrument shall be the date therein expressed as the date of the execution thereof, but where the instrument is made by 2 or more authorities jointly and is therein expressed to have been executed by those authorities on different dates, the date of the making thereof shall be the last date so expressed.
(2) Where a statutory instrument made or to be made after the commencement of this Act by one authority requires the concurrence or approval of any other authority, that concurrence or approval shall be formally inscribed on the instrument either—
(a) on or before the date of the making thereof; or
(b) if the other authority has before that date indicated an intention to concur in or approve of the making of the instrument, within 2 months after such making.