King George VI's Wembley Speech (Lost Recording of Speech; 1925)
King George VI of England was the reigning monarch of the British Empire during WWII and for a few years after. He was famous for having a very bad stammer (which is different than a stutter; stutter is a struggle to get through certain consonants, a stammer means the struggle to get a word out entirely) which made him incapable of performing many speeches during his role of Duke. Eventually, he started getting speech therapy from Lionel Logue, and he started working past his stammer to deliver some of the best wartime speeches during the war.
While many of George's speeches during the war survive, many of his pre-reign speeches are missing. Some were simply never broadcast or recorded; others were widely broadcast and somehow lost. The most famous of these speeches is his 1925 Wembley speech in which he stammered so badly that it literally took him hours to get through. The speech was an ordeal for both him and his audience. While nobody seeks out the speech for the sake of laughing at him, it is considered important for a frame of reference.
A short recreation of the speech was made for the opening scene to a 2010 movie titled The King's Speech in which Colin Firth played to role of King George. Firth would go on to win the Oscar for Best Actor, and the movie itself won Best Picture. Besides this reenactment, there is little that can be seen or heard of this famous speech.