Sprinkle the chicken generously with salt and pepper.
Cut a sheet of heavy duty aluminium foil about 45cm long. Place two thighs on the centre of the sheet, sprinkle with parsley and garlic and top with 3 lemon slices. Cover with another sheet of foil. Crimp the edges together and roll in towards the centre to make a tidy packet. Wrap in a third sheet of foil. Repeat with remaining thighs.
Heat a briquette barbecue until the coals are covered with white ash. Push the coals aside and put the chicken on the bottom of the barbecue. Cover with an even layer of coals.
Let cook 35 minutes, then remove from the barbecue and let stand 10 minutes before carefully opening.