Princes in the Tower act stated that Edward IV and Elizabeth Woodville's marriage was invalid because of Edward's pre-contract of marriage with Lady Eleanor Butler. Gloucester was crowned King Richard III of England on 3 July. The declaration of the boys' illegitimacy has been described by Rosemary Horrox as an ex post facto justification for Richard's accession. Dominic Mancini, an Italian friar who visited England in the 1480s and who was in London in the spring and summer of 1483, recorded that after Richard III seized the throne, Edward and his younger brother Richard were taken into the "inner apartments of the Tower" and
Princes in the Tower implicated in the decision to murder them, the hypothesis that he acted without Richard's knowledge is not widely accepted by historians. While Jeremy Potter suggested that Richard would have kept silent had Buckingham been guilty because nobody would have believed Richard was not party to the crime, he further notes that 'Historians are agreed that Buckingham would never have dared to act without Richard's complicity, or at least, connivance'. However, Potter also hypothesised that perhaps Buckingham was fantasising about seizing the crown himself at this point and saw the murder of the princes as a first step to achieving this