Section 111G. In any city or town in which the provisions of section one hundred and eleven apply and which accepts this section, in the manner hereinafter provided, any employee thereof who has worked continuously for five years but less than ten years shall be granted an annual vacation of three weeks without loss of pay, and any employee thereof who has worked continuously for ten years or more shall be granted an annual vacation of four weeks without loss of pay. Except as otherwise provided in this section, the provisions of said section one hundred and eleven shall continue to apply in such city or town. This section shall become effective in a city having a Plan E charter by the affirmative vote of a majority of all the members of the city council, and, in the case of other cities by vote of the city council, subject to the provisions of the charter, and in a town by a majority vote at an annual town meeting.