guard

The King's Guard (called the Queen's Guard when the reigning monarch is female) are sentry postings at Buckingham Palace and St James's Palace, organised by the British Army's Household Division. The Household Division also mounts sentry postings at Horse Guards, known as the King's Life Guard (called the Queen's Life Guard when the monarch is female).
An infantry contingent, typically one of the Household Division's five regiments of foot guards, mounts the King's Guard, while the King's Life Guard is usually provided for by the Household Cavalry Mounted Regiment. Since the 20th century, several other British Army units, Royal Air Force units, Royal Navy units, and military units from other Commonwealth countries have been invited to form the King's Guard.
In addition to the King's Guard, the Household Division also provide for several other sentry postings including the Tower of London Guard and the Windsor Castle Guard. Several sentry postings are also occasionally mounted at the Palace of Holyroodhouse, the sovereign's residence in Edinburgh. Although the Household Division considers these other sentry posts as distinct postings from the King's Guard, colloquially, these postings have also been called the "King's Guard."

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