After the Danish Reformation the priory was transformed into a manor estate known as Gavnø Castle located near Næstved, Denmark.
Later pirates used Gavnø as a base from which to attack Hanseatic vessels and raid coastal towns, so that the region long had a reputation for piracy.
The island was mortgaged by King Erik VI Menved in 1292 and eventually fell into the possession of the noble Falk family from Scania.
In 1398 Margaret I, queen of a united Denmark, Norway, and Sweden, purchased the island from Lady Ida Falk.
In return for the income, properties unmarried women lived a quasi-religious life in the security of St. Agnes Priory until they married or took vows.
In 1536 Denmark became a Lutheran kingdom under King Christian III and all religious houses and their income properties fell to the crown.
The prioress continued to maintain order inside the priory while a secular superintendent, Mogens Gøye (ca.
He was a staunch Lutheran and personally responsible for driving Franciscan friars from several friaries, but protected the women at St. Agnes Priory in his charge with honor and respect.
It was embellished by Lady Helle Rosenkrantz (1618-1685), widow of Niels Trolle into one of Denmark's most colorful churches and is the only visible remnant of the priory.