This annoying tourist found out exactly why you should never pester a Queen's Guard while he's on official duty - because you might get a gun pointed in your face.
In the clip, a man marches alongside the soldier as he paces up and down outside the royal residence.
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The pompous air of the tourist quickly turns to panic as he runs away.
That can be noted as another victory for the Queen's Guard over an ignorant tourist.
When will lessons be learnt?