Sterilise the jars you will be using.
If you don't have a cooking thermometer put a saucer in the freezer.
Add the blackcurrants and water to saucepan, bring the boil and simmer for around 5 minutes until all the fruit is lovely and mushy.
Turn the heat off and stir in the lemon juice.
Slowly stir the sugar in, letting it disolve gently.
Turn the heat back on and bring back to the boil, once boiling leave on the heat to rapid boil for 10 minutes or untill it reaches 105C, do not give in to temptation and stir while it is boiling. As soon as the 10 minutes is up turn the heat off.
At this stage If you don't have a cooking thermometer, remove the plate from the freezer and add a dollop of jam onto it. After two minutes push yoir finger slowly through the jam, if it wrinkles you know it's ready, if not, bring it back to the boil for two minutes, and then re-test it.
Take of the heat, skin off any froth, give it a quick stir and then landle into your steilised jars.
Place in a cool dry cupboard and enjoy at your pleasure.