Earl Castlemaine is in Earl Ireland.
On 11th December 1661 Roger Palmer 1st Earl Castlemaine [aged 27] was created 1st Earl Castlemaine, 1st Baron Limerick by King Charles II of England Scotland and Ireland [aged 31] in gratitude for allowing his wife Barbara Villiers 1st Duchess of Cleveland [aged 21] to become the King's mistress. Barbara Villiers 1st Duchess of Cleveland by marriage Countess Castlemaine. The title was to descend only to children of Barbara, which in effect, constrained it to her children with Charles. See Diary of Samuel Pepys, 7th December 1661.
In 1705 Roger Palmer 1st Earl Castlemaine [aged 71] died at Oswestry, Shropshire. His titles appear to not hve claimed by his children since they had been given their own peerages; Earl Castlemaine, Baron Limerick dormant.