I know the worst piece of "music" ever written. It is out of respect to the human race, of which the "performer" was not a part, that I have always refused to mention the name of this waste of vinyl or given any clue as to what it might be. Suffice it to say, I am not a violent person, but if I ever came close to the sub-human responsible, I'd punch him in the head, repeatedly. Showing the mediocrity of the audience of pop music, this excrement reached Number 1 in the UK. More than that, I'm not prepared to say.
I thought perhaps you were referring to 'MacArthur Park', but it only reached #4 in the UK... And Richard Harris was an excellent Arthur in 'Camelot'...