[1] He sat as a Member of Parliament for Carnarvonshire from 1761 to 1774, for St Ives from 1775 to 1780 and for Beaumaris from 1796 to 1807.

[2] He served as Lord Lieutenant of Carnarvonshire between 1761 and 1781 and raised and commanded the Carnarvon Militia.

[3] Lord Newborough married, firstly, Lady Catherine, daughter of John Perceval, 2nd Earl of Egmont, in 1766.

The couple had one child:[3] After Lady Catherine's death in 1782, Lord Newborough married, secondly, thirteen-year-old Maria Stella Petronilla, formally daughter of Lorenzo Chiappini (but maybe a member of the House of Orléans), in 1786; Maria Stella was born at Modigliana, near Forlì (Italy), in 1773.

Lady Newborough later remarried and became Baroness Ungern-Sternberg and died in 1843.