Section 59 of chapter 31 of the General Laws, as appearing in the 2006 Official Edition, is hereby amended by deleting the second  paragraph and inserting in its place the following:-

“An examination for a promotional appointment to any title in a police or fire force shall be open only to permanent employees in the next lower title in such force, except that if the number of such employees, or the number of applicants eligible for the examination is less than four, the examination shall be opened to permanent employees in the next lower titles in succession in such force until either four such eligible employees have applied for examination or until the examination is open to all permanent employees in lower titles in such force; such examination shall only be open to any person employed in such force, that has actually served at the lower title, on a permanent basis, for at least one year; and provided, further, that no such examination for the first title above the lowest title in the police or fire force of a city or town with a population in excess of fifty thousand shall be open to any person who has not been employed in such force in such lowest title for at least three years after certification.”