The ingredients and proportions are a long way from the original equal parts Scotch whisky and dry vermouth, but the result is a rather better cocktail...
This sort of subtle and elegant sipper of a cocktail always, irresistibly, invites us to fiddle...nothing fancy mind you. So initially we substituted, in turn, 7.5ml Mandarine Napoleon and 5ml Italicus for the 5ml Orange Curacao. Then we substituted Anejo Tequila for the Scotch, again reaching for the Mandarine Napoleon (at 7.5ml) as a substitute for the Orange Curacao. For us, the two versions with the Mandarine Napoleon were the loveliest. But of course the original is beautifully austere.
This is a beguiling little bite of a cocktail. Definitely important to keep the proportion of curaçao to 5ml or perhaps even less - a dash? - because it provides an integrating citrus background to the vermouths and whisky without overwhelming them with sweetness. I might even try it with orange bitters next, per one of those older recipes.