Mary Forbes, Countess of Granard British noblewoman (1670–1765) Parents Mary Stewart, Viscountess Mountjoy William Stewart, 1st Viscount Mountjoy Children Mary Preston Lady Mary Forbes Mary Preston John Forbes Nathaniel Preston Jane Preston George Forbes, 4th Earl of Granard John Preston Siblings Alexander Stewart Catherine Stewart Charles Stewart William Stewart, 2nd Viscount Mountjoy Partners George Forbes, 3rd Earl of Granard Phineas Preston