Preston studied in the English College, Rome, where he was taught by Gabriel Vasquez. He joined the Benedictine Order at Monte Cassino in 1590. Following the decree granted by the Inquisition and confirmed by Clement VIII in 1602 for a mission to the Benedictines in England, Preston and Anselm Beech were sent to England in the spring of 1603. They landed at Great Yarmouth and made contact with Sigebert Buckley, last survivor of the monks of St. Peter, Westminster, who had recently been released from imprisonment in Framlingham. They lived with Buckley, who by letters of 1607 and 1609 granted and confirmed to them authority to admit brethren to membership of the monastery and Congregation of which he had been the only surviving representative. To Preston, already the superior of the English of the Congregation of Monte Cassino, he entrusted the care of the English Congregation. Buckley died in 1610. Meanwhile, Preston had been indicted as a priest, and was soon afterwards imprisoned.