(b)where the aforesaid percentage has been first so held before the commencement of the Companies (Amendment) Act, 1974, on and from the expiry of the period of three months from the date of such commencement, unless within that period the aforesaid percentage is reduced below twenty-five per cent of the paid-up share capital of the public company, become, by virtue of this sub-section, a public company, and thereupon all other provisions of this section shall apply thereto: