Elderflower Champagne
Mother's Black Book
4 heads elderflower   Stand 24 hours. Strain, bottle in gas-proof bottles. Leave up to 1 month.
650g sugar  
2 tablespoons white wine vinegar  
5 litres water  
2 lemons lemons juice
chop rind coarsely
Makes 5 litres
For the real Cambridge experience, drink while punting to Grantchester.