One of the ceremonial sentries, known for their imperturbable solemnity inside the gates of the Queen's London residence, broke up his boredom last month while on duty.
Wearing the iconic red tunic and bearskin hat, the guard marched back and forth, pirouetting and at times walking in slow motion, then speeding up comically.
Spectators outside the gilded gates may have been entertained, but the Army is not amused. The Ministry of Defense confirmed he soldier will be disciplined.
"He is there to guard Buckingham Palace not provide horseplay for tourists," a senior military source told the Daily Mail, adding that he will likely face confinement to the barracks or see his pay docked.
"We are aware of the video," an Army spokesman said in a statement. "Anyone who is found to fall short of the Army's high standards can expect to face appropriate action."
Members of the Queen's Guard serve two-hour shifts before which they are read the rules: "You may not eat, sleep, smoke, stand easy, sit or lie down during your tour of duty."
While at their post, the soldier stand at attention, and every 10 minutes will slope arms, then do a march of 15 paces across the post four or five times before returning to the sentry box.