Pre-heat oven to 180°C, 350°F, Gas Mark 4.
Place the carrots, onions and cherry tomatoes into a large casserole dish. Sit the chicken on top and pour over the stock. Sprinkle over the Thyme and season well.
Cover with a lid and cook for 1 hour 25 minutes, basting occasionally with the pan juices. Remove the lid, add the lemon and cook for a further 20 minutes to brown.