Preheat the oven to 150ºC (130ºC fan) mark 2. Heat 1tbsp oil in a flameproof casserole dish and brown the beef in batches. Set aside. Add remaining oil to the pan and gently fry the onions and carrots for 10min until softened. Add swede and cook for 2min. Return beef to pan, sprinkle in flour and cook for 1min. Gradually stir in the Guinness and stock. Add sugar, Worcestershire sauce, bay leaf and thyme; bring to the boil. Cover and cook in the oven for 3hr.