1. Preheat oven to 220°C. Remove excess fat from chicken cavity. Wipe chicken inside and out with paper towels (see tip). Select a roasting pan with sides 4cm high.
2. Place lemon and thyme in chicken cavity. Tie chicken legs together with un waxed string and tuck neck flap and wings underneath. Combine butter and oil in a small bowl. Brush over both sides chicken. Place, breast side down, on a greased roasting rack in pan. Roast for 35 minutes.
3. Meanwhile, place potatoes in a saucepan and cover with cold water. Bring to the boil over high heat. Cook for 10 minutes or until almost tender. Drain. Return potatoes to saucepan. Cover to keep warm. Remove chicken from oven. Turn over and baste with butter mixture. Arrange potatoes around chicken. Brush with butter mixture.
4. Roast both for a further 37 minutes or until juices run clear when chicken thigh pierced with a skewer. Cover and stand for 15 minutes to rest. Carve chicken and serve with potatoes and steamed vegetables.