W. M. Ormrod
Henry of Lancaster [Henry of Grosmont], first duke of Lancaster (c. 1310–1361), soldier and diplomat, was the son of Henry, third earl of Lancaster (c. 1280–1345), and Maud Chaworth (d. 1317×22).
Plantagenet, Arthur, Viscount Lisle (b. before 1472, d. 1542), soldier, diplomat, and administrator, was the illegitimate son of Edward IV (1442–1483).
The identity of Arthur's mother and his date of birth have given rise to much speculation. The editor of his correspondence, Muriel St Clare Byrne...