The St Patrick halfpenny was a milled coin minted in the 17th century in England, Ireland and Wales. The reverse design shows King David kneeling playing a harp while gazing up at the royal crown of England. One peculiarity of the harp is that it bears a semi-nude winged female figure on the pillar, a feature which became common on English coins beginning in the second quarter of the 17th century. The legend on the obverse reads FLOREAT REX (May the King Flourish).
The obverse of the smaller copper halfpenny shows Saint Patrick dressed in bishop's garments wearing a mitre and holding a double-cross crozier. He is depicted dispelling the serpents from Ireland that are portrayed as various aquatic beasts, some are fabulous. In the background is purportedly St Patrick's Cathedral, Dublin. The legend reads QUIESCAT PLEBS (May the People Be at Peace).
On the larger copper specimens St Patrick is seen preaching to a crowd gathered round him. To his right is a shield with devices of several towers usually interpreted as three, suggesting the city shield of Dublin. The legend reads ECCE GREX (Behold the Flock). The majority of these St Patrick halfpennies are copper coins with a splash of brass minted in two sizes, large and small. Several known specimens exist in silver and one in gold, though reports of pewter and lead have also been made. The silver and gold specimens are minted on the smaller copper dies. The splash of brass on the obverse of the copper coins is intended to create the illusion that the royal crown that King David glances at is made of gold.
Where these coins were minted is still uncertain. One suggestion is they were minted at the Tower of London. When these coins were minted has been the subject of debate for the past two hundred and sixty years. Proposed dates for these coins have been 1641-1642; 1667-1669; 1672–1674. The current thinking is they were minted between 1646 to 1660 before the official reign of Charles II of England, while he was in exile, due to new documents recently discovered by John N. Lupia and published in the C4 Newsletter 2008. Who coined them and the circumstances surrounding them is still uncertain. Two candidates: Pierre Blondeau or Nicholas Briot have been proposed as the designer of these coins, but both the former suggestion seem unlikely. John N. Lupia has published in the C4 Newsletter 2009 new documentary evidence that shows both the small and large copper coins are halfpence. The small issue was minted 1646-1660, and the larger from 1688-1690.
One smaller copper specimen bears a counterstamp along the base of the obverse that reads MDLIII, which may suggest a date of 1553, but that is far too early to be taken seriously.
It is purported that about 450 different die varieties exist of this series on the small coin. Approximately 1,100 specimens are known in census. The number of coins minted has been guessed to be somewhere in the vicinity of approximately 1,500,000 to more than 7,000,000 pieces.
Sometime prior to 1678 an unknown quantity of these St Patrick coins were brought to the Isle of Man. An Act of Tynwald on June 24, 1679 demonetized them as of 15 January 1680, thus making subsequent specimens there extremely rare.
In 1681 it is supposed that Mark Newby, a Quaker who emigrated to Ireland, had brought a substantial quantity of these copper coins to North America when he relocated to West New Jersey, settling in Camden. On May 18, 1682 he was instrumental in having these coppers made legal tender in the region.
Numismatists classify the various die varieties according to the schemes proposed by Walter Breen and Robert Vlack giving them Breen or Vlack numbers followed by letters. The die varieties for the larger coin have been completely documented by Dr Roger Moore, Stanley E. Stevens and Robert Vlack, in the Colonial Newsletter 2005.