Anne was descended from King Edward through one of his older sons, Lionel of Antwerp, which gave her a claim on the throne after the death of her father and siblings. In about 1406, she married Richard, Earl of Cambridge, who was also descended from Edward III through a younger son. They had two children, Isabella and Richard, who later laid claim on the throne, beginning the Wars of the Roses. It is believed that Anne died giving birth to him.
Edmund was son of Roger Mortimer, 4th Earl of March by Eleanor de Holland, daughter of Thomas Holland, 2nd Earl of Kent and Alice Fitzalan.
Mortimer was reportedly approached by the conspirators at a late stage in the preparations, and after a period of about ten days informed the King of the threat against him.
The Earldom of Ulster, and his estates, passed to his nephew, AnneMortimer's son, Richard Plantagenet, later restored as 3rd Duke of York, who was nevertheless styled "Earl of March", as was his son, upon which son's accession to the Throne in 1461 as King Edward IV the Earldom of Ulster became extinct.
AnneMortimer (December 27, 1390 - September, 1411) was the daughter of Roger Mortimer, 4th Earl of March (1373-1398) and Eleanor de Holland.
Anne's husband plotted with Hotspur to raise their nephew, Edmund, 5th Earl of March to the throne thereby re-inforcing the claim of their descendants to the English crown at the expense of Henry V.
Anne herself was the heiress to the Earldom of March and the earl was not involved in the plot which, despite its failure, successfully promoted the claim of her descendants to the throne.