Used to enjoy watching these guys, what the shot doesn't show is that the toecap of the guard commander behind is probably only a few millimetres from the left-hand guardsman's derriere. Incredible watching them do it 'live'. And they maintain the one-handed grip on the rifle throughout the guard duty, swapping it from hand to hand periodically (every 5 minutes iirc) - they are not allowed to "slope arms" at any point.
Some of our youngsters could do with discipline like that. /forums/images/graemlins/laugh.gif
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Edit: wall looks like Kremlin - so Kremlin Guards?