Today I unstoppered it (as tonight's recipe could use something to deglaze a pan) and there was the unmistakable pop of a wine cork. It had fermented. After having been boiled on the stovetop for ten minutes, after being kept in the fridge for a week and a half. Boiled and chilled and adulterated with various sugars and spices (jaggery, clovetops and cassia I think?) it had nevertheless produced something pinkish, fizzy and mildly alcoholic. On its own yeast!
The vine has spoken. Does anyone have any old winemaking equipment gathering dust in a corner? Although from today's evidence, I could probably just brew this lot in a bucket.