colthurst was the son of john colthurst and alice conway. on 3 august 1744 he was created a baronet, of ardum in the baronetage of ireland. he served in the irish house of commons as the member of parliament for doneraile between 1751 and 1760, youghal between 1761 and 1768 and castlemartyr from 1769 to 1775.