Put the sausages and bacon or gammon pieces in a pan. Cover with water and bring just to the boil.
Reduce the heat, cover and simmer gently for 5 minutes. Drain, reserving the cooking liquid. Cut each sausage into three and remove the skin.
Preheat the oven to 2000C/ 4000F or Gas Mark 6.
Slice the potatoes and arrange the slices with the onion, sausage and bacon and in rough layers add seasoning, the thyme and half the parsley.
Make the reserved liquid up to 900ml (1 1/2 pints) with water if necessary, crumble in the stock cube then pour into the dish.
Cover tightly with buttered greaseproof paper then foil or a tight-fitting lid.
Cook for about 1 hour 30 minutes. Take off the cover after an hour or so to brown the potatoes on top, if you like, or brown them under the grill.
Sprinkle with more parsley before serving.