Melt the butter in a large saucepan and fry leek and onion for 4-5
minutes until the vegetables begin to soften. Stir in the turkey, carrot, potato and stock, bring to the boil and simmer for 15 minutes or until the vegetables are just tender.
Mix the cornflour with 2 tbsp of the milk and stir into the soup with the remaining milk and sweetcorn, simmer stirring until thickened. Add the parsley and season to taste. Keep warm.
Heat the oil in a large frying pan and fry the bacon until crisp - add the bread cubes and cook in the bacon fat until crisp. Scatter over the soup to serve.