Preheat the oven to 170C, 150C Fan, Gas Mark 3.Heat the oil in a large flame/ovenproof dish with a lid and cook the beef for 4-5 minutes until browned. Add the carrots, onion, leeks and herbs. Season well and pour over the stock and add the Worcestershire or brown sauce.Top with the potatoes, cover and cook in the oven for approximately 2-2 hours until the beef is tender.5-10 minutes before the end of the cooking time add the peas and return to the oven uncovered for the remainder of the cooking time.Simply serve this one-pot dish as is.