Boil the potatoes in water with a pinch of salt until soft.
Sweat the onions, garlic and carrots over a medium heat for 2-3 minutes until soft.
Once the potatoes are soft drain and mash with the butter and some salt
Add the lamb to the onions and brown off.
Mix gravy to package directions with warm water.
Add the chopped tomatoes, gravy mix and the ketchup to the meat and cook out until the right consistency (about 20 minutes)
Add the the meat mixture to an oven proof dish
Add the potatoes and grated cheese and bake in the oven for 20 minutes until golden brown.