The First Act of Succession was passed on 23rd March 1534 by Henry VIII.
The Act declared his daughter with Katherine of Aragon illegitimate, therefore changing Mary’s status from Princess to Lady. It paved the way for any children Henry had with his new wife, Anne Boleyn, to be the heir to the throne, with any boys would take precedent over girls. Anne’s first child was Elizabeth which made her heir to the throne unless Anne gave Henry what he ultimately desired – a boy.
Another part of the Act required all subjects to swear an oath to recognise Anne as his legal wife and any children they have the true heirs. It also demanded that Henry’s subjects recognise him as the head of the church. Anyone not swearing the oath was arrested under the Treasons Act. Some notable subjects that refused to take the oath included Sir Thomas More and Bishop John Fisher both were later executed for treason.
Henry later altered the act when he married Jane Seymour creating the Second Act of Succession, this Act declared Elizabeth illegitimate alongside Mary and pronounced his son heir to the throne. It was altered again in 1543 when Mary and Elizabeth were returned to the line of succession but behind Edward.
Tudor Chronicles 