Most Illustrious Order of Saint Patrick
The Order of
St. Patrick was founded in 1783 as an Irish equivalent of the
Order of the Garter and the
Order of the Thistle. There were originally 15
Knights of St. Patrick, but this was increased to 22 by
statute in 1833.
There were no more Knights of St. Patrick created after the Irish Free State was recognised in 1922, and the Order lapsed in 1974 with the death of the last surviving recipient, Prince Henry, Duke of Gloucester.
According to spiregrain: The cathedral in Dublin has all sorts of interesting MIOoSP bric-a-brac, including plumed helmets mounted over the choir stalls. - nice!