Rediscovering Saint Patrick: A New Theory of Origins sets out to answer the question of whether came from Britain or Brittany.
Four years of historical sleuthing has convinced Co Wicklow-based Church of Ireland clergyman Rev Marcus Losack that it was the latter.
On a visit to Chateau de Bonaban near St Malo in Brittany, he learned that the site on which the chateau was built contained remains dating from the Roman era.
Local tradition claims that the first building on the site belonged to St Patrick's father, Calpurnius, a Scottish noble who settled there to avoid Saxon forces who were invading Britain.
"At that time, this place was called Bonavenna de Tiberio. I was dumbfounded.
"In 'St Patrick's Confession' he told us he was taken captive when Irish pirates attacked his father's house at 'Bannavem Tiburniae' in Latin," Rev Losack said.
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