Pour in the stock, then add the chopped tomatoes, bay leaves, rosemary, thyme, potatoes, Worcestershire sauce and sausages. Give it all a good stir, scraping off any flavour from the bottom of the pan, then bring to a gentle simmer. Once simmering, turn the heat down to low, pop on the lid and leave to gently bubble away for 1 hour 30 minutes. Remove the lid, give it a stir, then simmer for a further 20–30 minutes, or until the sauce thickens.