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!").
Roger Moore recalled in his memoir that he told Jim O'Connolly that Finlay Currie's Scottish accent meant that he would have to be dubbed. O'Connolly replied, "Re-voice Finlay Currie? You can't re-voice Finlay Currie! He won the Oscar for playing Saint Peter with a Scottish accent! You'll go down in history as the man who had the temerity to dub this great actor".
Although Finlay Currie filmed this as a television episode, it transpired to be his final cinematic appearance, at the age of 90 and after an immense acting career.