The Comptroller and Auditor-General shall hold office for a term of six years from the date on which he assumes such office:
     Provided that where he attains the age of sixty-five years before the expiry of the said term of six years, he shall vacate such office on the date on which he attains the said age:
/      Provided further that he may, at any time, by writing under his hand addressed to the President, resign his office.
     Explanation.--For the purpose of this section, the term of six years in respect of the Comptroller and Auditor-General holding office immediately before the commencement of this Act, shall be computed from the date on which he had assumed office.