 The Earls of Loudoun would then, at least, be the heirs to the Yorkists.Upon Henry Tudor's uniting the rival houses of Lancaster and York, the title Duke of York became a royal prerogative and is traditionally accorded to the second son of the reigning monarch.Beginning with Richard of Shrewsbury (son of Edward IV, one of the Princes in the Tower), none of its holders were able to transmit it; they either died without a male heir or succeeded to the throne.