Osbert de Bayeux ( floruit 1121 to 1184 ) was a medieval English cleric and archdeacon in the Diocese of York . A relative of Thurstan , the Archbishop of York , Osbert probably owed his ecclesiastical positions to this relative . After Thurstan 's death , Osbert was opposed to one of the candidates for the archbishopric , William fitzHerbert , and worked to secure fitzHerbert 's deposition and replacement by Henry Murdac . After Murdac 's death in 1153 , Osbert tried to prevent the return of fitzHerbert , but these attempts were unsuccessful . When fitzHerbert died suddenly in 1154 , Osbert was accused of murdering the newly returned archbishop . Although he was never convicted of the murder in either a secular or an ecclesiastical court , he was stripped of his clerical status and became a layman before 1158 . He died after 1184 , perhaps even after 1194 .