Where the Director-General—
(a) refuses to grant any person a licence under section 16 of the Act; or
(b) grants any such licence subject to any conditions, or varies, adds to, or revokes any condition so imposed, under section 17 of the Act; or
(c) makes any decision adverse to an applicant for a licence in respect of any provision of section 18 of the Act; or
(d) cancels or suspends any such licence under section 20 of the Act; or
(e) refuses to grant a renewal of any such licence under section 21 of the Act,—
the Director-General shall forthwith give notice in writing of his decision and of the reasons therefor to the applicant for the licence or the licensee, as the case may be.