Thanks for making me dig this out. I'll try it again soon It's from Rose Elliot's Bean Book.
Boston Baked Beans.
12oz haricot beans
1 lge onion
1 tablespoon oil
i teaspoon dry mustard
2 teaspoons black treacle
1/4 pint tomato juice (or liquid from tin of toms)
2 tablespoons tomato puree
2 teaspoons brown sugar
1/2 pint unsalted stock
Serves 4
Soak, drain and rinse beans then cook in fresh water til they're almost tender, and drain again.
Set Oven 140'C (mark1). Peel and slice the onion. Heat the oil in ovenproof casserole and fry onion for about 5 minutes, then add the rest of ingreds and bring to boil. Cover and put in oven. Cook for FOUR HOURS stirring occassionally.