sansaregina:

25 June 1483: Anthony Woodville, 2nd Earl Rivers, is executed at Pontefract Castle

Gloucester had taken care of one last bit of business before becoming king: ordering the execution of Rivers, Grey, and Vaughan. Rivers made his will at Sheriff Hutton on 23 June, indicating that the execution order had been sent from London at least a couple of days before that.

Rivers’s will is a conventional one, in which Anthony is concerned with paying his debts, righting any wrongs he might have done, such as to Lady Willoughby, providing for the poor, and attending to the welfare of his soul. Perhaps anticipating that he would be brought south and given the trial in front of his peers that was his right as an earl, he asked that if he died beyond the River Trent, he be buried before Our Lady of Pewe at Westminster. 

Crowland is adamant that Rivers, Grey, and Vaughan were beheaded ‘without any form of trial’ under the supervision of Sir Richard Ratcliffe, who was leading Gloucester’s army south to London. John Rous, on the other hand, claims that Henry Percy, Earl of Northumberland, was their chief judge. No records of their indictments or trial, if there were any, have survived, nor is there any indication of who besides Northumberland sat in judgement of the trio. One is inclined to suspect that any process must have been summary even by contemporary standards; certainly nothing indicates that a jury of peers was summoned to try Rivers, as was his right under Magna Carta. 

– Susan Higginbotham -  The Woodvilles: The Wars of the Roses and England’s Most Infamous Family