Preheat the oven to 190°C.
Wipe the chicken dry, then rub inside and out with the butter.
Finely grate the rind of the lemon and lime, then squeeze out their juice. Mix the zest and juice with the oil.
Put ½ a lemon and ½ a lime in the cavity of the chicken together with the garlic and one bay leaf.
Place the chicken in a roasting dish. Scatter the remaining citrus pieces, the bay leaves and the thyme around the chicken. Season with salt and pepper, then pour over the citrus & oil mixture.
Bake for about 100 minutes, while occasionally basting the chicken with the resulting juices.
Insert a skewer between the thighs. If clear juice is coming out, the chicken is cooked through.
Take it out of the oven, transfer it to a plate, cover and rest for 15 minutes before serving.