The progenitor of the family was a companion of Strongbow, from whom he obtained grant for extensive lands in Waterford in the 11th century.

Lady Catharine grew up and married in 1717 an Irish politician, Sir Marcus Beresford, 4th Baronet.

[1] After the Jacobite rebellion of 1745, he was further elevated in 1746 as Earl of Tyrone in the peerage of Ireland (the same name of title as that of his father-in-law, but a new creation).

Lord Tyrone was succeeded by his fourth but eldest surviving son, the second Earl, who also inherited the title Baron La Poer from his mother in 1769.

In 1786 he was created Baron Tyrone, of Haverfordwest in the County of Pembroke, in the peerage of Great Britain.

As of 2015[update] the titles are held by the latter's great-great-great-grandson, the ninth Marquess, who succeeded his father in 2015.

William Beresford, seventh son of the first Earl, was Archbishop of Tuam and was created Baron Decies in 1812.

Lord William Beresford, third son of the fourth Marquess, was a soldier and recipient of the Victoria Cross.

He was one of several wild sportsmen who sprayed the tollgate and houses of Melton Mowbray with red paint.

[6] There are further male heirs in line to the earldom of Tyrone and its subsidiary titles, who are descended from the younger sons of the 1st earl.