Good line, bad attribution. I recall the comment from David Niven's memoir "Bring On the Empty Horses," where it was ascribed to English-language-challenged Hungarian director Michael Curtiz, who allegedly made the remark to Niven and Errol Flynn, having tired of their jokes at his expense during the filming of "The Charge of the Light Brigade" (1936). Curtiz also supplied the title of Niven's book, since he apparently requested riderless horses for one scene in "Light Brigade" by calling for empty horses. Ho ho.
I think your considerable output for the Guardian has taken a toll of your fact-checking ;-)
Carl