This is the hand of Mary (Howard) Fitzroy. Mary Howard (c.1519–1555) was the daughter of Thomas Howard, third duke of Norfolk, sister to Henry Howard, earl of Surrey, and the niece of Lord Thomas Howard. In late 1529, Henry VIII suggested to Norfolk that one of his daughters should marry his illegitimate son by Elizabeth Blount, Henry Fitzroy, duke of Richmond and Somerset. Mary Howard and Henry Fitzroy were married in 1533. See her full biography and contributions to the manuscript here.