Heat oil in a pan over high heat. Add beef and cook until it's nicely browned. Remove with a slotted spoon and set aside.
In the same pan, cook onions and celery until softened. Return the beef to the pan.
Mix flour and wine into a paste. Whisk in stock, Worcestershire sauce, sugar, and thyme. Add this mixture along with gravy browning (optional) to the pan. Bring to a boil, stirring to thicken. Add mushrooms and season with salt and pepper.
Cover and simmer for 45 minutes, or until the beef is tender. Adjust seasonings if needed.
Boil sliced potatoes in salted water for 4-5 minutes until softened but not mushy. Drain well.
In a baking dish, spread the cooked meat and preheat oven to 425°F (220°C).
Layer half the cooked potatoes on the meat, followed by half the cream. Repeat with remaining potatoes and cream. Season in between layers.
Sprinkle cheese on top and bake for 30 minutes, or until golden brown and bubbly.