 Formerly, the rank of king's counsel not only precluded a barrister from appearing against the Crown, but, if he was a member of parliament, entailed that he give up his seat.A patent of precedence was resorted to as a means of conferring similar marks of honour on distinguished counsel without any such disability attached to it.The patents obtained by Mansfield, Erskine, Scott, Jervis and Brougham were granted on this ground.