It is true that no trace of this temple has been discovered; but the conjecture is not inconsistent with the known principles of the early Christian missionaries, in their contact with paganism, as illustrated in the history and traditions of other important churches. Stow's phrase, "long before the Conquest," though somewhat ambiguous, has been thought to point to a date posterior to the Roman occupation. Some authorities, therefore, contend that the Romans had erected London Bridge and left the country before St. Mary's was founded, and consequently the bridge the antiquary mentions as built by "Swithun, a noble lady," was not the first. Again, it is doubtful whether the sub-title "Overie" means "of the ferry," or "over the river," or whether the form "Overies," which the word sometimes takes, does not suggest a derivation from "Ofers," "of the bank or shore," a meaning contained in the modern German _Ufer_. John Overy, or Overs, was the father of Mary, but whether the surname was derived from the place, or _vice versa_, is uncertain. In any case, the name, whether by accident or design, includes a reference to the foundress as well as to the locality of her foundation.[2] Stow is obviously wrong, however, as to the person who converted the House of Sisters into a College of Priests, who was not a lady, but St. Swithun, Bishop of Winchester (852-862), whose devotion to the building of churches and bridges is well known. The character of the foundation, altered by St. Swithun, was again altered in 1106, under Bishop William Giffard, with the co-operation of the two Norman knights to whom Stow refers. They not only erected the first Norman nave, but made a radical change within by abolishing the "College of Priests," in whose place they introduced "Canons regular" of the Augustinian Order, governed by a Prior, thus transforming the Collegiate Church into a monastery. Except as regards the sex of the inmates, the change was a reversion to the idea of the foundress.[3]