In a non–stick saucepan, fry the lamb mince on a high heat for 5 minutes or until nicely browned. Turn down the heat and add the onion, carrot and celery and continue to cook for 2 minutes. Spoon in the tomato puree and pour in the red wine and cook for 3-4 minutes. Add the water, worcestershire sauce and rosemary. Stir well and simmer for 20 minutes. Spoon in the Bisto Best Lamb Gravy, this will instantly thicken the cooking liquor. Place into a baking dish and allow to cool slightly.
Preheat the oven to 180°C fan.
Grate the potato and celeriac and place in a clean dish cloth to ring out the moisture, place in a mixing bowl, add the butter, oil and seasoning and gently mix. Scatter the mixture over the lamb covering everything.
Bake in a hot oven for 30 - 35 minutes or until the potato is browned and everything is piping hot. Suggestion: Serve with tenderstem brocolli and more gravy