Not a lot of people know that Richard II had a paternal half-brother. This was Sir Roger of Clarendon, born at at unknown date to Edward of Woodstock, the 'Black Prince' and one Edith de Willesford.
He was almost certainly older than Richard II, and in 1372 received an annuity of £100 from Edward III.
In 1402 Roger was arrested, accused of conspiracy against his cousin, Henry IV. He may have been guilty of spreading rumours that Richard was still alive. He quite possibly believed that he was. In any event he was executed at Tyburn - which suggests he was hanged, drawn and quartered for high treason.
My main source for this is Plantagenesta