The situation from the video footage beneath this text does not often happen at Whitehall London, but horses can be unpredictable and you never know what will happen next. Clearly, something has been bothering this horse and during guard change he reared and fell.
That guard has shown what a great rider he is by going after the horse after the fall has happened. He tried to calm down the animal and acted like a real professional. Luckily, both of them were fine and had no injury.
Maybe that horse was just having a bad day, and sometimes we are not able to notice if something is bothering our horse. They don’t freak out for no reason and maybe we can’t see things the way they can, and that’s why we can’t predict some moments.
Every horse rider should be careful and watch over their horse, be prepared for the unpredictable and keep calm no matter what. That is what is going to protect you and your horse from getting injured!