Remove the berries from their stalks before washing and then squashing them down with a fork. Place them in a pan, cover with water and bring to a brief boil while stirring. Sieve the blackcurrant juice through a fine sieve or cheesecloth. Then stir in 400g sugar and bring to the boil again. Pour into sterilised bottles while hot.
Note: Hildegard von Bingen was the first to recommend blackcurrants as a remedy. They contain up to five times more vitamin C than lemons and have the highest potassium content of all berries (300mg) – they help to reduce blood pressure and are highly effective at eliminating fluid. They also contain minerals such as magnesium, calcium, phosphorus and iron, as well as antimicrobial agents and antioxidants. Thanks to their antibacterial properties, currants are also used to treat throat inflammation, to reduce fever in cases of inflammation, colds and influenza, and, when heated up, to alleviate coughs.