Queen's guard SHOUTS outside Windsor Castle when over-eager tourist steps the mark trying to get the perfect photograph: 'Stay away!'

Queen's guard SHOUTS outside Windsor Castle when over-eager tourist steps the mark trying to get the perfect photograph: 'Stay away!'

Queen Elizabeth could be left red faced when she sees the viral video of her guardsman shouting at a tourist [Mumby/Indigo/Getty Images]

Queen Elizabeth's guards are known for their composed exterior and extreme discipline, and are rarely seen to flinch under the advances of testing tourists.  

However, recent hilarious video footage has shown that even royal staff can sometimes loose their cool, even during the most official of duties.

The video begins by showing four of ...