Heat the oven to Gas Mark 2, 150ºC, 300ºF.
Put all the ingredients, except the cranberries, in an ovenproof casserole with a lid.
Put on a gentle heat, season, stir well then cook for 10 minutes until the butter has melted and everything is well mixed.
Cover, transfer to the oven and cook for one hour. Add the cranberries and cook for a further 30 minutes or so until completely tender.
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