Preheat the oven to 180°C, fan 160°C, gas 4. Place the leeks, bay leaf, onion, pepper, garlic, thyme, stock and tomatoes in the base of a large casserole and mix together well.
Place the chicken on top, cover with a tight-fitting lid and place in the oven. Roast for 45 minutes.
Carefully lift the chicken away from the veg and put to one side. Add the basmati rice and peas. Stir well then return the chicken. Drizzle the olive oil over the top of the chicken and return, uncovered, to the oven. Roast for a further 15 minutes until the rice is tender and has absorbed most of the liquid, and the chicken has turned golden brown on the breast and tops of the legs.
Remove the chicken and transfer to a carving plate. Leave to rest for 10 minutes before carving.
Serve the sliced chicken with the rice and vegetables.