The titles of Viscount Mountjoy and Baron Stewart of Ramelton in the Peerage of Ireland were conferred upon Sir William Stewart, 3rd Baronet, of Ramelton, in 1683.
His grandson the 3rd Viscount Mountjoy was created Earl of Blessington in 1745 and died in 1769, when all his peerage titles became extinct (though the baronetcy remains extant).
Alexander Stewart and granddaughter of the 1st Viscount Mountjoy, married in 1711 Luke Gardiner, who served as Vice-Treasurer of Ireland.
His son Charles John Gardiner, 2nd Viscount Mountjoy, was created Earl of Blessington, again in the Peerage of Ireland, in 1816.
[1] Charlotte Jane Windsor, daughter of the 2nd Viscount Windsor and 2nd Baron Mountjoy, married the 4th Earl of Bute, and that nobleman was created Marquess of Bute, Earl of Windsor and Viscount Mountjoy in the Isle of Wight in 1796, in the Peerage of Great Britain.