Elderflower Cordial Recipe

There are loads of elderflower bushes in the garden (grounds, land, whatever) and we feel compelled to make things from them. Having made some Elderflower Champange we moved on to cordial which keeps longer and takes more elderflowers to make.

15 elderflower heads (remove stalks if you want - apparently they can give a bitter taste but I have never had a problem)
1 liter water
1 kg white sugar
33g citric acid (available from health food shops or brewing shops)
1/2 a lemon cut in to slices

Mix sugar and water in a pan and bring to the boil (stir until sugar dissolved)
Boil for a few minutes
Turn heat off and add citric acid, sliced lemon and elder heads
Cover and leave over night
Strain and bottle in to sterilised bottles (we use old swing top beer bottles and sterilise by running through dish washer)