Place beef and plain flour into a large bowl and toss to coat.
Place a large heavy based pan over medium heat and add 1 tablespoon olive oil. Add meat and cook for 2-3 minutes or until meat is brown. Remove meat from the pot and set aside.
Add remaining olive oil to the pan and cook onions, garlic and leek for 1-2 minutes, or until just softened. Add carrots, sweet potato, swede, celery, beef stock, water, diced tomato, parsley, Worcestershire sauce and beef to the pot and bring to the boil.
Reduce heat, cover and cook on low heat for approximately 2 hours, stirring approximately every 20/25 minutes.
Garnish fresh parsley on top of beef stew.