"Widow's Prior Service Annuity" shall be credited for the widow of a male present employee for service prior to the effective date, in accordance with the "Firemen's Annuity and Benefit Fund Act of the Illinois Municipal Code" and this Article.
For a present employee in service on August 31, 1957, and under age 57 on that date, the annuity so provided shall be improved by interest at 4% per year during his subsequent service. For a present employee in the service on August 31, 1957, and over age 57 on that date, the annuity so provided shall be improved by interest at such rate in the manner stated in Section 6--132 of this Article.
40 ILCS 5/6-129