British PM bombs history pop quiz from Letterman (VIDEO)

David Letterman grilled British Prime Minister David Cameron on history trivia Wednesday night in the first-ever appearance by a serving British head of state on the popular US late-night comedy television show. 

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Letterman, known for his acerbic wit and merciless interoggations, began by asking Cameron if he knew who composed the British patriotic song Rule Britannica. "Elgar?" hazarded the British PM. Nope. Next! 

Where was the Magna Carta signed? Cameron looks confounded, but correctly states the year (1215). Good save. How about the meaning of Magna Carta?

That's, like, Latin, right? 

Crickets. From The Independent: 

“Oh it would be good if you knew this – we’ll find it,” Letterman jabbed.

Team Briton, we, the inventors of humour allegedly, were left in the dust by the funny American – who’d have thought it?  

This was perhaps not the gracious welcome the British leader had anticipated. 

The Guardian's New York correspondent, Oliver Burkmen, was not amused: 

Letterman's randomly lobbed history trivia questions … seemed entirely without purpose. Letterman spent much of the rest of his time asking deliberately dumb questions: What is the deal on Wales? – while Cameron spent his trying to sneak in references to the London Olympics. … All of which only served to underline what an odd decision it had been for Cameron to … appear on Letterman's show. Not because of the host's alleged rapier wit (yes, he's smarter than Jay Leno, but so are some crustaceans) but because there could never have been any upside. It could only prove embarrassing, or be forgotten.

Watch it all here, thanks to The Telegraph: