Well now, this is interesting:

"Many sites credit Monty Python as the creators of this work. However, it is my belief that this is incorrect and the author of the original shorter version is still unknown. The later, longer version which is well known to many people is actually credited to the late Jack Wagner, the former 'voice of Disneyland'. It is said that Mr Wagner received an audio tape copy of the original which he then improved upon, added a musical track to and re-released. His name appears to have been omitted due to the conflict of interest with his position with Disneyland and his desire not to be fired."

You learn something new every day.