Wow, it really is old. There probably are so many cocktails which were made decades ago, but never saw the light of day, only for a bartender decades later to claim it as the original. As always, thanks for everything you do Simon, and thanks for your input, Ian.
For the record, it was fantastic with the cheap Jules Larose VSOP Armagnac I just tried it with.
I feel it’s probably one of those cocktails that will really reward you if you find the right combination, as opposed to something like a Sabot that will taste at least OK with almost any bottle-shelf combination.