Wash and drain the fruit and put into a greased preserving pan or thick based saucepan and cook gently to extract some juice then simmer until fruit is soft.
Bring to the boil and simmer gently, stirring occasionally to prevent sticking, until the fruit breaks down and the skins are soft, (about 1/2 hour) and the contents of the pan will have reduced considerably.
Add the sugar and stir until dissolved, then boil rapidly to setting point, about 10 minutes.
Pot and cover in the usual way; label and date. (See 'Potting and covering' for details).