Preheat the oven to 220°C/425°F (convection/fan assisted).
Roughly chop the carrots, celery and leek into large chunks and halve the garlic along its equator. Lay these vegetables across the base of your roasting pan with sprigs of rosemary and thyme. Toss with a little olive oil or goose fat.
2 medium carrots, 2 sticks celery, 1 leek, 2 heads of garlic, 4 sprigs fresh rosemary, 4 sprigs fresh thyme
Place your whole chicken on top of the vegetable trivet and rub with 2 tablespoon olive oil or goose fat. Sprinkle the salt and pepper all over the chicken and rub all over into all the creases around the wings and legs too.
3-4 pound free range chicken, 2 tablespoons olive oil, 1 teaspoon sea salt, ¼ teaspoon freshly ground black pepper
Place the chicken into the oven and immediately turn down the temperature to 180°C/350°F. Roast for 20 minutes per pound plus 20 minutes, basting every 30 minutes with the fat and juices accumulating in the base of the pan. Until an internal reading of 74°C/165°F on a digital thermometer.
For a 4 pound chicken that would be 20 x 4 = 80 minutes, plus 20 = 100 minutes. Which works out at 1 hour and 40 minutes roasting time.
Once finished roasting, leave the chicken to rest on a platter for 20 minutes before carving and serving. Meanwhile use the vegetables and juices in the bottom of the roasting pan to make your gravy.