The Guards at Buckingham Palace are the reason the world doesn't speak French... or German.
At Waterloo the Coldstream guards defended the forward redoubt of Hougomont against an entire French Army corps while the Grenadiers decisively repulsed the breakthrough attempt of Napoleon's Guards.
In Spain the Guards acted as the rearguard allowing the army to stand at Corunna before their evacuation.
In 1940 they acted as the rearguard at Calais, buying time for the evacuation at Dunkirk. They aren't just chocolate soldiers, tellingly the intelligence level to enter the guards is only higher than the pioneers (trench diggers) and The Parachute Regiment. If you are going to ask people to face almost impossible odds, it's best they can't really figure out the consequences.