When the Queen of England goes to visit the City she is met by the Lord Mayor at Temple Bar, the symbolic gate of the City. She bows and asks for permission to enter his private, sovereign State. During such State visits "the Lord Mayor in his robes and chain, and his entourage in medieval costume, outshines the royal party, which can dress up no further than service uniforms."
The Lord Mayor leads the queen into his city.
The symbolism is clear. The Lord Mayor is the monarch. The Queen is his subject.