Remove the clavicle and discard on both sides of the breast. Lay the barding fat over the breast of the chicken and tie into place with some string while trussing the chicken. Rub the fat and the skin with a little lemon juice.
Line the bottom of the roasting pan with the bacon. Place the chicken on top of the bacon and place in the oven. During cooking, baste the chicken every 10 minutes with the stock mixed with the demi-glace.
When the chicken is cooked — 65 to 68°C measured in the thigh — remove from the oven and tent with foil and a couple of towels for 15 minutes. Defat the cooking juices and set aside.
Carve the breast of the chicken into thin slices. Remove the legs and thighs. Arrange the some chicken breast and either a leg or thigh on each heated serving plate and spoon the sauce over the chicken.