Heat oil in a large flameproof casserole or non-stick deep frying pan over medium-high heat. Add meat in batches and brown on all sides, about 5 minutes per batch. Place in a bowl.
Add the potato, carrot, onion, leek and turnip to pan. Cook 10 minutes; stir occasionally. Stir in flour. Add 3 cups water, bay leaf, rosemary, salt and pepper. Bring to the boil. Reduce heat. Add meat. Simmer, uncovered, until meat is tender, 50 to 60 minutes. Add peas. Simmer 5 minutes; serve.