Home Made Wines, Syrups and Cordials. by the National Federation of Women's Institutes, 1957
Pick the Elderflower heads when in full bloom and put into a bowl followed by the lemon juice, cut up rind (no white pith), sugar and vinegar. Add the cold water and leave for 24 hours. Strain into strong bottles, cork firmly and lay them on their sides. After two weeks it should be ready to drink. This is a summer drink, rather like lemonade.