The origin of the red saltire which is described as the Cross of Saint Patrick has often been explained by reference to the Order of the Knights of Saint Patrick, which was instituted in 1783. It is said that prior to this there was no heraldic symbol associated with Patrick and that the red diagonal cross was borrowed from the arms of the Fitzgerald family and included in the coat of arms of the Order.
However a flag bearing a red saltire was carried by the Catholic Confederates in 1644.
Even before that in 1612 a saltire appeared in the arms of Trinity College.
But the most significant fact, as regards a connection between the cross and Patrick, is that a saltire was featured on the old seal of the Dean and Chapter of Armagh.
This earlier use of the saltire tends to disprove the Fitzgerald explanation of the origin of the cross.