A conductor's licence issued or renewed under the Act or the Rules made thereunder shall:-
(i) if the person obtaining the licence, either originally or on renewal thereof, has not attained the age of forty years on the date of such issue or renewal,
(a) be effective for a period of twenty years from the date of such issue or renewal,
(b) until the date on which such person attains the age of forty years, which ever is earlier,
(ii) if the person referred to in clause (i) has attained the age of forty years on the date of issue or, as the case may be, renewal thereof, be effective for a period of five years from the date of such issue or renewal:
Provided that every conductor's licence shall, notwithstanding its expiry under this Rule, continue to be effective for a period of thirty days from such expiry.