Heard the same joke with George Bush...
Another Bush and the Queen story:
While visiting England George W. was treated to a ride in the Royal carriage.
Down the main thouroughfare, one horse let go with a particularly loud and smelly one.
Embarrasseed, the wqueen turned to Bush and said: "I'm sorry Mr. President, you must realize some things even a Queen can't control."
Bush replied: 'Think nothing of it , Your Majesty- until you said something, I thought it was the horse."