The baronetcy, of Carrickdrumrusk in the County of Leitrim, was created in the Baronetage of Ireland in 1660 for his father, Oliver St George.
Before his elevation to the peerage, Lord St George had represented Carrick in the Irish House of Commons.
Olivia Ussher, sister of Lord St George, married Arthur French.
Their son Christopher French assumed the surname of St George in lieu of his patronymic.
Sir Richard St George, grandfather of the first Baronet, was Clarenceux King of Arms.