Heat oven to 200C/180C fan/gas 6. Sit the chicken in a roasting tin, skin-side up, and surround with the potatoes and halved tomatoes, cut-side up.
Scatter the tomatoes with a light sprinkling of sugar (this helps to bring out their natural sweetness). Scatter the thyme leaves and sprigs over the tin, season and drizzle with oil.
Roast for 45 mins until the chicken and potatoes are cooked through with crisp, golden skin.