Who was the legal grandson of the Earl of Merica?
Ælfgar, Earl of Mercia Ælfgar (died c. 1060) was the son of Leofric, Earl of Mercia, by his famous mother Godgifu (Lady Godiva). He succeeded to his father's title and responsibilities on the latter's death in 1057. He gained the additional title of Earl of East Anglia, but also was exiled for a time. Through the first marriage of his daughter he would become father-in-law of the Welsh king Gruffydd ap Llywelyn; a few years after his death, his daughter would become a widow and marry English King Harold.
Roger Mortimer, 4th Earl of March Roger de Mortimer, 4th Earl of March and 6th Earl of Ulster (11 April 1374 – 20 July 1398) was a 14th-century English nobleman. He was considered the heir presumptive to King Richard II after the death in 1382 of his mother Philippa of Clarence (a granddaughter of King Edward III of England) until his own death in 1398.