Based on the novel "Vendetta For The Saint", published under Leslie Charteris' name, but ghostwritten by Harry Harrison ("Deathworld", "The Stainless Steel Rat", and "Make Room! Make Room!").
Findlay Currie's (Don Pasquale) voice is dubbed to sound more Italian.
Ian Hendry also appeared in the "Yesterday's Hero" episode of The Return of The Saint tv series (1978)