3E+W+SSubject to the following provisions of this Schedule, any such certificate issued by the Board—
(a)if not renewed, shall cease to have effect at the end of the period of five years beginning with the date on which it was issued, or
(b)if renewed, shall, unless further renewed, cease to have effect at the end of the period of five years beginning with the date as from which it was renewed or last renewed, as the case may be.