Add all the ingredients to a preserving pan and cook, uncovered, over a gentle heat for 1¾–2 hours, stirring from time to time, but more frequently towards the end of cooking as the chutney thickens.
Ladle into warm, dry jars, filling to the very top and pressing down well. Disperse any air pockets with a skewer or small knife and cover with screw-top lids. Label and leave to mature in a cool, dark place for at least 3 weeks.
To serve, this chutney is delicious as part of a ploughman's lunch.