I assume you mean the British Composer. that would have to be Pomp and Circumstance sometimes called the Graduation march . I believe it was written in l902 so when they use it for the ceremonial...
* Eine Kleine Nachtmusik * The Marriage of Figaro * Don Giovanni * The Magic Flute * Symphonies 39, 40, 41 * Piano concertos 17, 20, 21, 23, 27 * Violin concertos 5, 6 * Flute and Harp concerto *...