Complex sentence: He was elevated to the peerage in 1720 as Baron Beresford and Viscount Tyrone, and in 1746 he was created 1st Earl of Tyrone (third creation) and the Beresford-Power family have held the estate ever since.
Split into simpler sentences: He was elevated to the peerage in 1720 as Baron Beresford and Viscount Tyrone, and in 1746 he was created 1st Earl of Tyrone (third creation). The Beresford-Power family have held the estate ever since.