Petrus,
The coin you illustrate is a silver penny of the titled issue of 1463.
The original coin is copper so if it is Irish it belonges to an earlier anonymous issue in 1460/61.
The reverse cross looks right for the issue - but the crown is not right at all. The coin I am thinking has a quite small crown in the centre (smaller than the one on the later silver penny) and the legend Patric around the crown - but it does have a feature in the legend which may correspond to the base of what the original poster is identifying as the crown.
My only example of this rare issue is here :
http://www.irishcoinage.com/J01272.HTM as you can see the crown is very small.
The obverse is so unclear that I am unable to confirm the identification, but I am not aware of any other coin of this period which has the plain cross reverse that this one has.
Most coins in this grade would be pretty much worthless - but these Irish copper pieces are so scarce that even very poor examples have a value - I seem to recall paying over £100 for my poor example in a Spink auction many years ago.
John.