Where the last day of any period mentioned in sections 109(1) and 110(1) of this Act falls on a day on which the office of the Clerk of Justiciary is closed, such period shall extend to and include the next day on which such office is open.

Any period mentioned in section 109(1) or 110(1)(a) of this Act may be extended at any time by the High Court in respect of any convicted person; and an application for such extension may be made under this subsection and shall be in as nearly as may be the form prescribed by Act of Adjournal.