Preheat oven to 400°F.
Heat a large, deep skillet or Dutch oven over medium-high to high heat with oil, 2 turns of the pan. When oil ripples, add meat and brown well, stirring occasionally. Add onions, carrots, celery, garlic, bay leaves and season with salt and pepper. Cook to soften vegetables, 10-12 minutes. Stir in Worcestershire sauce and reduce heat to simmer.
In a small skillet, melt butter over medium heat. Whisk in flour, cook 1 minute then whisk in cider or beer. Reduce by half then whisk in stock and thicken to a loose gravy.
Place meat and vegetables in a casserole dish and stir in watercress and gravy. Top with cheddar and tots, and bake until tots are golden and crispy on top.