 John de Vere, 12th Earl of Oxford, and his eldest son and heir, Aubrey, were beheaded on 26 February and 20 February, respectively, after the discovery of an alleged plot to murder Edward IV.No records of the trials of the alleged conspirators have survived to shed light on what part, if any, Tyrrell's father played in the alleged conspiracy.He was not attainted, and his eldest son and heir's wardship and the custody of his lands were granted to Cecily Neville, Duchess of York, who sold them to William Tyrrell's widow in March 1463 for £50.