This is a useful and delicious way of using thinnings from a vine. The grapes should be about the size of peas. Wash them and cover with water. Simmer until soft and strain through a jelly bag. Measure the juice and allow 1lb/450g sugar to each pint/500ml juice. Heat the juice gently, stirring in the sugar until dissolved. Boil hard to setting point. Pour into small hot jars and cover.