Some thoughts on the name Patrick -

First a yarn.
A new worker turned up on a job I was working on. His name was Sullivan*. It turned out that he had relatives all over the construction industry and most of the blokes had worked with one or other of these Sullivans.
Anyway somebody asked, "What's your name then?" "My names Ignatius*" he said, "but I prefer Paddy." OK, Paddy it was. When we started work I walked to the job with Big Jack*. "Why does he want to be called Paddy?" he asked me.
"If you were called Ignatius wouldn't you want to be called something else?"
"Yeah, but why Paddy?"
"I'm guessing his middle name's Patrick."
"Yeah, but why Paddy?"
Now I'm stumped. What was it the big fellow didn't get?
"He can call himself what he likes" was my last throw of the dice, and the exchange ended on that unsatisfactory note.

I puzzled about Big Jack's continued inability to understand Paddy's choice of name. Finally I got it. He didn't recognise Paddy as a diminutive of Patrick, he thought it was just a generic nickname for an Irishman. Probably all the Paddies he'd ever met were Irish, while this lad was English-born. Big Jack probably thought the lad was assuming a fake identity.
Sometimes the gaps in people's knowledge takes us by surprise.

Now and then someone would ask me why one of my sons was called Patrick, "That's an Irish name." They'd say, sometimes with indignation during the bomb-happy 1970s. "No it's not", was my reply, "it's a Scots name." They thought I was talking through my tóin (Irish word), but history is on my side.
Before the beginning of the 18th century very few Irishmen bore the name of their patron saint. A couple of so-called 'Norman' families used the name - Fitzmaurices and Sarsfields. Others might use a Gaelic construct, Giolla Phadraig, 'Servant of Patrick'. English records would often translate this name as Patrick.
Meanwhile, over in Scotland the place was crawling with Patricks. The Scots believed that the saint was a native of Dumbartonshire, Alcluyd in his day. Paterson is a common Scots surname and there are plenty of others denoting descent from a Patrick or Padruig; Paton, Pate, Patrick, McFadyean and McFadden, McFetridge.
With the arrival of Calvinism baptismal names from Celtic saints were discouraged, as they were associated with feast days, holy relics, holy wells, and other popish frippery. Names like Mungo, Duthac, Fillan virtually disappeared. Only the Episcopalians and the remaining Catholics continued to use them, and among such families the name Patrick survived.

Why did the name became popular among the Irish as it was losing its grip on the Scots?
One suggestion, by Edward MacLysaght, is that the death of Patrick Sarsfield, "Ireland's darling", in France brought the name to their attention, and it was in his memory that they embraced the name.
George Fraser Black, however has another suggestion. The settlers who came to Ireland during the Scottish Plantation of Ulster brought the name over, and the Irish adopted it as the Scots were discarding it.
My own opinion is that the process was helped by the gradual transition from Irish to English as the majority language. It became acceptable in English to give a child a saint's name without preceding it with Giolla literally 'servant', but more loosely 'disciple, devotee'.

Anyway, today is Saint Patrick's Day.

*Name changed to avoid identification.