The General Clauses Act, 1897
§19 — Official chiefs and subordinates
(1) In any [Central Act] or Regulation made after the commencement of this Act, it shall be sufficient, for the purpose of expressing that a law relative to the chief or superior of an office shall apply to the deputies or subordinates lawfully performing the duties of that office in the place of their superior, to prescribe the duty of the superior. (2) This section applies also to all [Central Acts] made after the third day of January, 1868, and to all Regulations made on or after the fourteenth day of January, 1887.