(1) If, in the opinion of the Director of Finance and Planning, the exigencies of the public service render it necessary or expedient to vary the sum assigned to any purpose within a supply vote shown in the estimates of expenditure for any financial year or to make provisions for a new purpose within that vote, he or she may direct by means of a virement warrant under his or her hand that there shall be applied in aid of any purpose for which the sum assigned may be deficient or in aid of any new purpose a further sum out of any surplus arising from under-expenditure on any item within the same supply vote.
(2) In the exercise of his or her powers under subsection (1) the Director shall ensure that—
(a) the sum appropriated for any supply vote by the Appropriation Act or by a supplementary Appropriation Act is not thereby exceeded; and
(b) any new purpose to which a sum is assigned is within the ambit of the vote.