[4] The priory dates back to around the year 1100, when one of Hugh de Lacy's knights called William reputedly came upon a ruined chapel of St. David in this location; he was inspired to devote himself to solitary prayer and study.

In 1135, after persistent attacks from the local Welsh population, the monks retreated to Gloucester where they founded a secondary cell, Llanthony Secunda.

The buildings at Llanthony gradually decayed after the Dissolution to a ruin although, in the early 18th century, the medieval infirmary was converted to the Church of St David.

Landor needed an Act of Parliament, passed in 1809, to be allowed to pull down some of Wood's buildings and construct a house, which was never finished.

However, the idyll was not to last long as, for the next three years, Landor was worried by the combined vexation of neighbours and tenants, lawyers and lords-lieutenant and even the Bishop of St David's.

After an expensive action to recover the debts from Betham, Landor had had enough and decided to leave the country, abandoning Llanthony to his creditorschurch of – principally his mother.

In 1869, Joseph Leycester Lyne (known as Father Ignatius) founded an Anglican monastic institution in nearby Capel-y-ffin, which he named Llanthony Abbey.