Cut the potatoes into 1cm slices and put them into a saucepan of cold water. Bring to the boil and simmer for 4 or 5 minutes, until parboiled (half cooked). Drain and leave to cool.
Peel the garlic and put the cloves in a mini food processor. Add the rosemary leaves, the butter, then grate the lemon zest into it. Season to taste. Blend until you get a coarse paste.
Using your fingers, ease the paste under the skin all over the chicken - be careful not to tear the skin.
Cut the lemon in half and put into the cavity.
Layer the potato slices and lardons in a large roasting tin. Place the chicken directly on top (or on a wire rack placed in the tin above the potatoes). Pour over the wine, season with salt and pepper.
Cook for about an hour and a half until the chicken is cooked through and the potatoes are soft.
Rest the chicken (covered) for 10 minutes.
Serve with the bacony potatoes and steamed vegetables or green salad.