Rub the chicken quarters all over, quite hard, with the cut lemons. Place the chicken quarters in a bowl or shallow dish. Add the oregano, thyme, olive oil, garlic and rubbed lemon halves and mix everything together well. Cover with clingfilm and leave to marinate in the refrigerator for at least 2 hours.
Meanwhile, make the yogurt sauce. Pour the yogurt into a bowl and beat until smooth. Mash together the garlic and salt in a bowl, then stir into the yogurt with the dill. Set aside.
Transfer the marinated chicken to a roasting tin and roast in a preheated oven, 200°C (400°F), Gas Mark 6, for 35–45 minutes, spooning over a bit of the marinade now and then if the chicken looks too dry or burnt. To test whether the chicken is cooked through, pierce at the thickest point with a skewer – if the juices run clear, it is ready.
Serve with the yogurt sauce and a big plate of piping-hot chips and salad leaves.