Cheese soup with beans and bacon

Name: Cheese soup with beans and bacon
Cook time: 30 min
Total time: 30 min
Cuisine: European, British
Ingredients: 2 onions; 30g butter; 200g smoked pancetta, in one piece; 2 carrots; 1 stick celery; 4 sprigs thyme; 3 bay leaves; 400ml milk; 45g plain flour; 1 litre chicken or vegetable stock; 2 tsp grain mustard; 700g butter beans, bottled or tinned; 350g cheddar; Chopped parsley, small handful