Section 57B. Any member of a police or fire department of a city or town, who retires under the provisions of sections fifty-six to sixty, inclusive, and who was appointed a reserve police officer or call fire fighter shall, for the purpose of retirement, be entitled to count as creditable service such service as a reserve police officer or call fire fighter as the retiring authority shall determine.

This section shall take effect in a city having a Plan E charter when accepted by an affirmative vote of two thirds of the city council and approved by the city manager, in the case of other cities by a two-thirds vote of the city council and approval by the mayor and in a town by a majority vote at the annual town meeting.