Bill Waddington and Lilian Waddington, playing the monocled tourist and his lady, were genuinely married in real-life.
Vine's Duckie Clubs are an obvious riff on the Playboy Bunny Clubs, the first of which was founded in Chicago in 1960. 1965 saw the company's first overseas venue selected, at London's 45 Park Lane, making the plot highly contemporary.
As Oldenshaw correctly notes, "Never explain and never compromise" is a saying attributed to former British Prime Minister Benjamin Disraeli.