To add to my previous post...
St. Patrick stamps aren't published every year, though Ireland did produce St. Patrick Day covers, similar to first day covers with cachets, but using current definitive issues. I have three of these that came in an auction lot a while ago, dated March 17, 1976, 1977, and 1978. I'll try to remember to get scans when I'm on the computer with the scanner.
With St. Patrick's Day coming, it could be a good time to get them up on
ebay.

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