His Britannic Majesty or, when the reigning monarch is female Her Britannic Majesty (HBM),[1] is a treaty title for the monarch of the United Kingdom, a royal style used in international law and diplomacy.
Many other monarchies in Europe used similar conventional terms as treaty titles to identify their respective monarchs.
Initially, His/Her Britannic Majesty referred to monarch of the Kingdom of Great Britain.
It is not, however, invoked in agreements signed between the United Kingdom and the other Commonwealth realms, because the monarch cannot contract with themselves.
Examples include: His Britannic Majesty's Secretary of State Requests and requires in the Name of His Majesty all those whom it may concern to allow the bearer to pass freely without let or hindrance, and to afford the bearer such assistance and protection as may be necessary.