Retroactive birther movement

However, the allegations of King Edward’s illegitmacy was purely circulated by partisans of Warwick the Kingmaker and later of Richard III, and maligns Cicely (Neville) York, Duke Richard’s wife, who was still alive through the Wars of the Roses and both her sons’ reigns, dying in 1495 with Henry VII and his wife, Elizabeth of York, Cicely’s granddaughter, on the throne.

Right. It wasn’t the Tudors who claimed that either Ed IV or Ed V were illegitimate. It was Richard III who done it.

I challenge you to find a contemporary account of Richard or his partisans prompted by him claiming that. It would have traduced his mother, his wife, and his sister-in-law, all of whom lived quite comfortably with Richard during his reign; sister-in-law Elizabeth (whom no one blamed for her illegal marriage, as Edward had kept it secret) accepted a pension from him.

Tudor writers later claimed that Richard said it, but I’m not aware of any contemporary evidence to that effect.