Beef & vegetable casserole

INGREDIENTS

• 2 celery sticks, thickly sliced
• 1 onion , chopped
• 2 really big carrots , halved lengthways then very chunkily sliced
• 5 bay leaves
• 3 sprigs thyme
• 1 tbsp vegetable oil
• 1 tbsp butter
• 2 tbsp plain flour
• 2 tbsp tomato purée
• 2 tbsp Worcestershire sauce
• 2 beef stock cubes , crumbled
• 850g stewing beef (featherblade or brisket works nicely), cut into nice large chunks