Section 44. No veteran, as defined in section one of chapter thirty-one, in the service of the commonwealth or of any county, city or town therein, except policemen, firemen, and members of the office of public safety and inspections of the division of professional licensure or the division of inspection of the department of fire services doing police duty, shall be required to perform any service on Memorial Day. Such veterans, if employed as policemen or firemen by any city or town, may be granted leave of absence without loss of pay on Memorial Day by the governing authorities in cities and towns.