Noun
An usher in the British royal household.
(historical) A high-ranking servant responsible for overseeing the work of other servants.
Source: en.wiktionary.orgBlack Rod's Garden (named after the office of Gentleman Usher of the Black Rod ) is closed to the public and is used as a private entrance. Source: Internet
Black Rod (as the Gentleman Usher is normally known) is responsible for ceremonial arrangements, is in charge of the House's doorkeepers, and may (upon the order of the House) take action to end disorder or disturbance in the Chamber. Source: Internet
The Gentleman Usher of the Black Rod's duties may be delegated to the Yeoman Usher of the Black Rod or to the Assistant Serjeant-at-Arms. Source: Internet