For the reduction, combine the Madeira, port, shallots, garlic, thyme, bay leaf and pepper in a heavy-based saucepan over medium–high heat. Bring to the boil and cook until the mixture has reduced by half, about 6–10 minutes. Add the lamb stock and reduce by half again, about 3–5 minutes. Remove the pan from the heat and allow the reduction to cool before straining and r