1. Heat oven to 220C. Clean chicken and wipe dry. Tuck lemon, two garlic cloves and two thyme sprigs into the cavity, and tie legs together with kitchen string.

2. Coat chicken with dabs of butter, scatter with sea salt, pepper and oregano, and place in a lightly oiled baking tray.

3. Cut potatoes in half lengthways and cut each half lengthways into three wedges. Coat potatoes, carrots, eschallots and remaining garlic cloves in olive oil, and arrange on a baking tray lined with baking paper. Strew with half the remaining thyme and half the rosemary and bake for one hour in the oven with the chicken.

4. Roast the chicken breast-side down for 15 minutes, then turn breast upwards and roast for a further 45 minutes, until the skin is golden and the juices run clear when pierced.

5.Rest chicken for five minutes. To carve, remove legs and cut leg joints in two, then slice breast meat at a slight angle. Serve with vegetables, watercress and remaining thyme and rosemary.

Tip British chef Heston Blumenthal suggests seasoning the bird generously inside and out with salt and freshly ground black pepper.

This is one of Jill Dupleix's 10 recipes everyone should master.