|SOME NOTES ON MEDIEVAL ENGLISH GENEALOGY|
Volume 7, page 227:
He [Gerald FitzMaurice (FitzGerald), Earl of Kildare (d. 1432)] m., 2ndly, before 18 Nov. 1397, Agnes DARCY; the Pope on that day granting an indulgence to Gerald FitzMaurice, Earl of Kildare, and Agnes his wife. ... As Agnes Darcy, Countess of Kildare, she occurs in July 1414.
Douglas Richardson, in June 2002, pointed out that Agnes's daughter Elizabeth and her husband James Butler, earl of Ormond (d. 1452) were said to be doubly related, one of the relationships being given as the 3rd and 4th degrees of kindred, on the side of James's father and Elizabeth's mother [citing Calendar of Papal Letters, vol. 8, pp. 442, 443].
The relationship probably came through James's paternal grandmother, who was a daughter of Sir John Darcy, Lord Darcy (d. 1347). The stated degree of kindred could be explained if Agnes were a great granddaughter of this Sir John Darcy. She may therefore have been a daughter of his grandson Philip (d. 1399), who was sent to Ireland in 1392 to recover his inheritance [Complete Peerage, vol. 4, p. 62].