Overview
An equerry (; from French 'stable', and related to 'squire') is an officer of honour. Historically, it was a senior attendant with responsibilities for the horses of a person of rank. In contemporary use, it is a personal attendant, usually upon a sovereign, a member of a royal family, or a national representative. The role is equivalent to an aide-de-camp, but the term is now prevalent only among some members of the Commonwealth of Nations.
Australia
Australian equerries are commissioned officers in the Australian Defence Force, appointed on an ad hoc basis to the King of Australia, Governor General, state governors or to visiting foreign heads of state.
Canada
Canadian equerries are drawn from the commissioned officers of the Canadian Armed Forces, and are most frequently appointed to serve visiting members of the Canadian Royal Family. The equerry appointed for the King of Canada is a senior officer, typically a major or a lieutenant-commander, while the equerry appointed for a child of the monarch is a junior officer, typically a captain or naval lieutenant.
Canadian equerries are also sometimes appointed to serve national representatives of the country. In 2007 Hal Jackman (former lieutenant governor of Ontario) was the equerry to Akaash Maharaj, in the latter's role as head of Canada's tent pegging team.
From Wikipedia (CC BY-SA 4.0).