PRIVY COUNCIL OF IRELAND

The 'Privy Council of Ireland' (Irish; ''Comhairle na Banríona'') was an institution of the Kingdom of Ireland until 31 December 1800 and of the United Kingdom of Great Britain and Ireland 1801-1922. It performed a similar role in the government of Ireland to that the Privy Council of the United Kingdom did in the United Kingdom.
A member of the Privy Council of Ireland who was a commoner was styled Right Honourable, just as the members of the British Privy Council were. A Lord of the Privy Council could append the initials PC after his title, as he would already have the title of Right Honourable (or a higher one like Most Honourable) as a peer.
For an incomplete (but substantial) list of members of the Privy Council of Ireland see Leigh Rayment's site.