For the beans, heat the olive oil in a wide heavy-based pan over a medium-high heat. Add the pancetta and fry for 1-2 minutes, or until starting to crisp at the edges, then stir in the onion and garlic.
Fry for 2-3 minutes, until the onion is translucent, then stir in the paprika, mustard, treacle, Worcestershire sauce, to taste, tomatoes, sugar, tomato purée and haricot beans. Bring to a boil and cook for ten minutes, or until the liquid has reduced to a thick consistency. Season with sea salt and freshly ground black pepper
Meanwhile, for the meatballs, remove the casing from the sausages and roll the sausage meat into golf ball sized pieces. Heat the olive oil in a frying pan over a medium heat and fry for ten minutes, turning regularly, or until golden-brown and cooked through.
For the potato cakes, boil the whole potatoes for five minutes or until just tender. Drain and, when cool enough to handle, coarsely grate into a mixing bowl. Add the spring onions, flour and half the butter. Season with salt and freshly ground black pepper and mix well. Divide into four equal balls and pat into flat rounds.
Heat the oil and remaining butter in a large non-stick frying pan over a medium heat and gently fry the potato cakes for 2-3 minutes on each side, or until golden-brown and cooked through.
To serve, spoon the beans over the potato cakes and meatballs and garnish with the parsley.