As made on the farm's "Sunflowers and Sundials" event recently.....
36 elderflower heads
2 lemons, sliced
6 pints water
1.5 lbs sugar
2 tbsp white wine vinegar
1) Pick fragrant creamy flowerheads on a sunny day (some say before midday).
2) Shake any insects off flowerheads. Put flowerheads into a clean bucket with the sliced lemons, pour the water on top, and leave to soak for 24 to 36 hours, stirring occasionally.
3) Strain through muslin and add the sugar and white wine vinegar.
4) Stir until the sugar is completely dissolved, then pour into clean plastic bottles with screw-top lids (you can use glass bottles, but beware of explosions as this gets very fizzy!).
5) Store in a cool place for 2 weeks. If bottles start to bulge let off a bit of gas and re-screw. Drink within 2 months.