UK's PM left embarrassed on TV show

United Kingdom's Prime Minister appeared on the US David Letterman TV late night show that turned out to be a nightmare for the British leader as he failed to get key questions right when quizzed by the host on his knowledge of British history and culture.

Being the first serving British prime minister to appear on the US popular chat show hosted by Letterman, the British ruler showed some gaps on his general klnowledge.

The Eton and Oxford-educated Prime Minister could not explain the meaning of 'Magna Carta' and gave an incorrect answer when asked by the US host to name the composer of Rule Brittania.

Remarking on his errors, Mr Cameron joked: "That is bad. I have ended my career on your show tonight."

The PM was welcomed on to the show to the tune of the house band playing Rule Britannia and dry ice pumping into the studio to replicate London fog.

After a brief discussion of issues surrounding Syria and the Arab Spring - the subject of his speech to the United Nations earlier in the day - Letterman confronted him with a truly tough question - who wrote Rule Britannia?

A floundering Mr Cameron made a guess at Edward Elgar, only to learn from Letterman's researchers that it was in fact the little-known Thomas Arne, setting words by James Thomson to music.

He was also at a loss for an answer when asked for the English translation of Magna Carta - Great Charter - and hesitated a while before naming Runnymede as the location of its signing.

But he immediately named 1215 as the date it was drawn up and was able to give an account of its importance in the birth of democracy.