William Kingsmill alias William Basyng was Prior of the Benedictine St. Swithun's, Winchester until the Dissolution of the Monastery in 1539. He was appointed as the first Dean of Winchester Cathedral at the foundation of the new chapter in 1541.
William Kingsmill was professed to the Rule of Saint Benedict at St. Swithun's Priory (Winchester Cathedral) in 1513. Upon joining the Benedictine Monastery he took on the name of his home town Basyng and was known as William Basyng until 1540. During his time as a monk, Basyng obtained several secular appointments. Bishop Foxe of Winchester ordained Basyng as a Deacon in 1521. Two years later, Basyng was fully ordained as a priest. During his time as a monk, Basyng studied logic, philosophy and theology, and was granted the degree of Bachelor of Theology by University of Oxford on June 1, 1526. Over the next three years, Basyng participated in four public disputations on theology, and received his licence to preach in January 1529. His final disputation was presented on February 4, and he received his Doctorate in Theology on March 15, 1529.
Basyng became a leader within the priory due to his education and experience with the outside world as a secular cleric. In 1529, when Henry VIII summoned the Reformation Parliament, he also summoned a meeting of Bishops, Deans, Priors and leading monks and clergy to a Convocation of Canterbury. Basyng was summoned as a representative for St. Swithun's, along with his prior, Henry Broke. Basyng may not have attended, though Prior Broke seems to have been present. As a lesser clergyman, Basyng's selection to the Convocation singled him out for future promotion, such as then Archdeacons Stephen Gardiner and Thomas Cranmer.