Hairy Bikers Leek and Potato Soup

Ingredients

• A large knob of butter
• A medium onion, chopped
• 3 large leeks, white part only, sliced
• 5 potatoes, peeled and diced
• 3/4 pint of vegetable stock
• 100 ml of double cream
• Worcestershire sauce
• Salt and pepper
• Parsley, chopped (optional)
• Wensleydale cheese, grated (optional)