Set the oven to 200deg, put a large roasting tray in the oven and allow to get piping hot. Then once the tray is hot add oil, tomatoes, onion, garlic and thyme. Allow to roast until the skins turn black and the tomatoes are a pulp. In a pot reduce the tomato juice by half, then add the roasted tomatoes, brown sugar, worcester sauce and chicken stock. Allow to simmer for 15 mins then add the basil. In a food processor blend the soup until smooth. Season the soup with salt and pepper and add the balsamic.