Charter of the Forest (1225) - Clause 11

(11) Whatsoever archbishop, bishops, earl or baron, coming to us at our commandment, passing by our forest, it shall be lawful for him to take and kill one or two of our deer, by view of our forester, if he be present; or else he shall cause to blow a horn for him, that he seem not to steal our deer. And likewise they shall do returning from use, as it is aforesaid.