Preheat the oven to 180C.
Heat the oil in a large frying pan and fry the sausages over medium heat until browned all over. Transfer to a casserole dish and add the celery and carrots.
In the same pan, fry the onions, bacon and garlic for around 5mins until they begin to soften. Transfer to the casserole dish.
Add the ale to the pan to deglaze, then add in the stock tomato puree, sugar, bay leaf and Worcester sauce. Bring to a gentle boil and pour into the casserole dish, stir in the parsley and cover and place in the oven for around 1hr – 1.5hrs until the vegetables begin to soften.
When vegetables are cooked, stir in the cornflour and return to the oven for another 10 minutes until the sauce has thickened.
Remove from the oven, season with a large pinch of salt and pepper, sprinkle with the remaining parsley and serve alongside some mashed potato, little roasties of simply a warm French bread