(CNN) -- While Saint Patrick's Day has long been the preserve of Guinness-drinking revellers painting the world's towns green while wearing shamrock hats, Irish Catholics have always taken pride in their nation's patron saint.
Now a new study from Cambridge University based on his writings suggests Saint Patrick was not brought to Ireland as a slave, as the legend has it, but that in fact he may actually have sold slaves his family owned to pay his way to Ireland -- in order to avoid a job as a tax collector for the Roman empire.
The findings fly in the face of the classic account of the life of Saint Patrick, who grew up as a member of the Roman nobility in western Britain and was supposedly abducted and forced into slavery in Ireland around 400 A.D. According to this history, Patrick escaped and became a priest before having a vision and returning to Ireland to convert the Irish to Christianity.
Legend has it Saint Patrick used the shamrock, now the national emblem of Ireland, to explain the concept of the Holy Trinity, by showing an unbeliever the three-leafed plant with one stalk.
The new study, based on Patrick's own writings in their historical context, argues that Patrick actually ended up in Ireland in order to avoid becoming a "Decurion," or Roman tax collector -- a role in city government that had become undesirable and dangerous in Patrick's time.
"In the troubled era in which Patrick lived, which saw the demise and eventual collapse of Roman government in Britain in 410, discharging the obligations of a Decurion, especially tax-collecting, would not only have been difficult but also very risky," said Dr. Roy Flechner, from the Department of Anglo-Saxon, Norse and Celtic at Cambridge University.
Patrick's father was a Decurion, which was a hereditary role, and when he vacated his position in order to join the clergy, Flechner says Patrick chose to leave Britain to avoid being obligated to take up his father's job.
In order to get to Ireland, which lacked a monetary system at the time, Patrick would have needed to sell commodities to finance the trip. According to his writings, Patrick's family owned several slaves -- a high value and easily transportable commodity -- and Flechner says in the historical context it makes sense that Patrick would convert his family wealth into slaves he could sell in order to pay his way.
But Philip Freeman, author of the biography "St. Patrick of Ireland," says while it is almost certain that Patrick's family owned slaves, as many members of the Roman nobility did at the time, experts' claims that Patrick himself was a slave trader is reading too far into the sources.
"It's almost certain that Patrick grew up surrounded by slaves, but there's no good reason for thinking he was a slave trader," Freeman told CNN.
"The only sources we have about Patrick that are really reliable are the two letters he wrote when he was an old man," he said. "And both of those tell the story of a young man who grew up in the young Roman nobility in Britain, but was kidnapped when he was 16 years old."
Cambridge University's Roy Flechner believes the widely accepted history of Saint Patrick's early life and kidnapping was largely concocted by Patrick himself in those letters.
"The traditional story that Patrick was kidnapped from Britain, forced to work as a slave, but managed to escape and reclaim his status, is likely to be fiction: the only way out of slavery in this period was to be redeemed, and Patrick was never redeemed. The traditional legend was instigated by Patrick himself in the letters he wrote, because this is how he wanted to be remembered," he said.
Flechner says it is only Patrick's motives, and not his efforts to Christianize the Irish people, that are up for debate.
"None of this is to say that Patrick was not a bishop or that he did not engage in missionary activity, but his primary motives for moving to Ireland were most likely to escape the poisoned chalice of his inherited position in Roman Britain," he added.
While very little is known about Saint Patrick, one legend has credited him with having driven the snakes out of Ireland.
However, most biologists maintain there never were snakes in Ireland.