Sir Thomas More, p.
482.
It was also maintained that the act of attainder passed against the duke of Clarence, had virtually incapacitated his children from succeeding to the crown; and these two families being set aside, the protector remained the only true and legitimate heir of the house of York.

But as it would be difficult, if not impossible, to prove the preceding marriage of the late king, and as the rule which excludes the heirs of an attainted blood from private successions was never extended to the crown, the protector resolved to make use of another plea, still more shameful and scandalous.

His partisans were taught to maintain, that both Edward IV.

and the duke of Clarence were illegitimate; that the duchess of York had received different lovers into her bed, who were the fathers of these children, that, their resemblance to those gallants was a sufficient proof of their spurious birth; and that the duke of Glocester alone, of all her sons, appeared by his features and countenance to be the true offspring of the duke of York.

Nothing can be imagined more impudent than this assertion, which threw so foul an imputation on his own mother, a princess of irreproachable virtue, and then alive; yet the place chosen for first promulgating it was the pulpit, before a large congregation, and in the protector's presence.
Dr.Shaw was appointed to preach in St.Paul's; and having chosen this passage for his text "Bastards lips shall not thrive," he enlarged on all the topics which could discredit the birth of Edward IV., the duke of Clarence, and of all their children.