1. Add the flower heads into a jug or bowl and then to this add the sliced lemon.
2. To a pan add the sugar, citric acid (you can get this at the pharmacy) one Campden tablet (optional) and 1 litre of water. Heat until all of the sugar has dissolved then, carefully add the hot sugary solution onto the elderflower and sliced lemon.
3. Leave for one day to infuse preferably in a dark cupboard.
4. Filter the cordial through a clean tea cloth or muslin into freshly washed and dried glass bottles.
5. Keep cool. ideally store in the fridge, good for 3 months but it won’t last that long!