Who was the legal grandson of the Earl of Merica?
Ealdgyth, daughter of Earl Ælfgar Ealdgyth ("fl. c". 1057–1066), also Aldgyth or in modern English, Edith, was a daughter of Ælfgar, Earl of Mercia, the wife of Gruffudd ap Llywelyn (d. 1063), ruler of all Wales, and later the wife and queen consort of Harold Godwineson, king of England in 1066. She was described by William of Jumièges as a considerable beauty.
Countess of Derwentwater Amelia Matilda Mary Tudor Radclyffe, soi-disant Countess of Derwentwater, was a 19th-century claimant to the estates of the Earls of Derwentwater. She claimed to be the granddaughter of John Radclyffe, only son of the third Earl, and in 1860 commenced to agitate for her rights, initially contacting Lord Petre as the representative of descendants of the family using the name of Lady Matilda Radclyffe.