Here he laboured for some years converting the Picts and Saxons. After Sigeberht was slain by an army led by Penda of Mercia, it is recorded that his successor King Anna of East Anglia, and his nobles, further endowed the monastery at Cnobheresburg. Three miracles are recorded of Fursey's life in this monastery. He then retired for a year to live with Ultan the life of an anchorite. However, as great numbers continued to visit him, and as war threatened in East Anglia, he left Foillan as abbot and proceeded to Lagny, in France around 644.