President Obama and, in his own way, George W Bush before him, are also Pyles. Bush argued vociferously for democratic reform in the Middle East. Obama, in a speech in Cairo in 2009, presented a more pragmatic approach – support for the citizenry, but less criticism of the dictators. Much has been made of that difference, and the argument has been made that Obama's shift put him behind the march of history, first in Iran after the 2009 elections and now in Egypt.

It is true that Washington's responses seem tame, but in reality the difference is overplayed. America faces the same fundamental dilemma that the former power Britain failed to resolve in the decades leading up to the Suez Crisis. Do you trust 80 million Egyptians to determine their own foreign policy, in this most vital of regions? It takes a braver superpower than Britain to say yes.

In a former age, British armour surrounded the royal palace to stop the king siding with Nazi Germany. Now the balance of power is maintained in more subtle ways, but another turning point has arrived nevertheless.