The monarchy is one of the greatest, though least observed, checks on arbitrary power. It occupies the space a dictator would need to occupy.
Because it is unthinkable in Britain to push the monarch aside, tyranny itself becomes unthinkable. In countries where for understandable reasons the monarchy was overthrown — France in 1789, Russia in 1917, Germany in 1918 — tyranny was not unthinkable. […]
In modern times, our monarchs have served the public by going above politics, and becoming instead a kind of hereditary umpire.
The Queen plays this role with exceptional and unwearying conscientiousness. She does not have to declare any Prime Minister out: the public elect MPs who do that for her.
But she stops the politicians, few if any of whom remain popular for long, from getting above themselves, and obliges even a convinced republican such as Jeremy Corbyn to play by the rules.
The Queen, Mr. Gimson writes of the U.K., “upholds our constitution.”