Lady Catharine grew up and married in 1717 an Irish politician, Sir Marcus Beresford, 4th Baronet.
After he died in 1763, Lady Catharine, now the Dowager Countess of Tyrone, had petitioned the Irish House of Lords to restore to her the "Barony de la Poer", which she asserted was created by writ for her grandfather Richard Power.
The petition was based on another writ received by Nicholas (fitz John) le Poer, of Kilmeadan, who was summoned to the Parliament of Ireland on 23 November 1375, 22 January 1378, and 11 September 1380.
Nevertheless, on 9 November 1767 the Irish House of Lords resolved that she had proved her case; the Crown confirmed this on 19 December 1767 and allowed her "all the rights and privileges belonging to the said Barony", as they had been held by "her grandfather Richard, who sat and voted as Baron La Poer".
When the Dowager Countess died, 27 July 1769,[3] any title she may have held passed to her son George, 2nd Earl of Tyrone, who was promoted to Marquess of Waterford in 1789, as part of the British government's effort to manage Grattan's Parliament; all his titles are held today by Henry Beresford, 9th Marquess of Waterford.
A barony by writ is a typical creation of English common law, but aside from this case, they are now almost non-existent in the Peerage of Ireland.