Fry the beef in the frying pan until golden brown and set it aside. It helps if you do it in smaller batches in a large, fairly hot pan.
Use the same pan for frying the onion and celery. Fry until the vegetable starts to soften and return the meat to the pan.
Whisk the wine and flour in a bowl to create a smooth mix, then whisk in the stock and add the liquid to the pan together with Worcestershire sauce, sugar and thyme.
Bring to simmer and stir regularly while the sauce is thickening.
Add mushrooms and gravy browning (optional); season with salt and pepper.
Cover the pot with a lid and simmer for 45 minutes. Add more liquid if needed and occasionally stir as the flour tends to stick to the bottom.
Bring water to a rapid boil. Carefully insert potato slices into the water, give them a stir or two, and cook for 5-7 minutes with the lid on. Carefully drain the potatoes and let them cool down a bit.
Preheat the oven to 220C/fan 200C/Gas 7.
Cover the bottom of the roasting dish evenly with the cooked meat filling. Arrange half of the potatoes on top. Season with salt and pepper and pour over half of the cream. Place the other half of the potatoes on top of the first layer. Season again, pour over the rest of the cream and sprinkle with the grated cheese.
Bake in the oven for around 30 minutes or until the top is golden brown.